Jennifer Lopez & Casper Smart

Casper Smart did NOT cheat on Jennifer Lopez with two transsexuals -- and he's prepared to sue the website that claims he did ... so says Casper Smart.

As TMZ first reported, JLo and Smart split up a few months back ... and it had nothing to do with Smart's alleged sexcapades.

But Smart is pissed that TheDirty.com claimed he had flings with two transsexuals he met on Instagram ... so his lawyer has fired off a letter to the site's founder, Nik Richie, denying he's ever met, kissed or had sexual relations with either of the transsexuals in question.

Smart says he didn't send them dirty pics and flat out denies cheating on Jennifer.

Smart has given the site an ultimatum -- either retract the story or get sued.

Smart's lawyer also sent a threatening letter to one of the transsexuals who has been talking to the media ... imploring her to sign a declaration saying they never met Smart.

TMZ reached out to Richie for a response ... and here's the part we can post: "Casper, go get a real job. I heard Instagram is hiring over in their compliance department ... Stop blaming everyone else for your problems."

Casper Smart went looking for a Jennifer Lopez replacement in a target rich spot -- the Maxim Hot 100 party -- but the choreographer had trouble attracting babes with his moves on the dance floor.

Sources inside the party Tuesday night tell TMZ ... Smart was there with his boys, including Wilmer Valderrama.

We're told things got weird when Smart -- who remember is a dancer by trade -- hit the floor by himself, and busted out some crazy moves?

Some people felt he was trying to steal the spotlight by dancing solo near a giant video screen that was flashing photos of the hot 100 babes.

But the best moment was when #36 ... J.Lo popped up on screen. We're told Casper kept his head down the whole time to avoid seeing her pic.

Casper Smart is keeping some fabulous parting gifts in the wake of his breakup with Jennifer Lopez ... but he's not getting any cash ... he's now strictly on his own.

Sources connected with the former couple tell TMZ ... Casper gets to keep 2 motorcycles, a jeep and a Dodge Ram truck.

Pretty sweet so far, but that's where it ends. Casper's days tooling around L.A. in that white Bentley are over. Ditto flying private jets, the fancy Hamptons mansion and the Hidden Hills estate.

The toughest change for Casper -- he won't be sitting front row during Paris Fashion Week with Kanye.

And there's this. Our sources say Jennifer won't be doling out any money for Casper to land on his feet, but we're told that's the way he wants it. As it was put to us, "He's too much of a man" and hasn't asked for anything.

Well, Melanie Griffith is gonna be single soon ...

Vivid Entertainment honcho Steve Hirsch sent a letter to Casper ... asking him to play the lead love interest in an XXX film featuring the transsexual with whom he was rumored to have an online fling.

Hirsch says Sofie Vissa is locked and loaded for a film called, "Sofie on the DownLo" ... and Hirsch wants Casper to get it on with Vissa in the company's first-ever transsexual sex tape.

We're told Casper is being offered around $200,000 -- with big back end potential and the possibility of a sequel, "Casper, the Friendly Host."

Casper has not acknowledged any sort of relationship with Sofie.

Jennifer Lopez and Casper Smart's break-up has nothing to do with any new relationships he may or may not have ... according to people close to them.

So hypothetically speaking, if a couple of attractive transsexual women are into Casper -- J.Lo hypothetically doesn't care ... cause she's been done-zo for a while.

Jennifer Lopez and Casper Smart have called it quits after nearly 2 1/2 years ... TMZ has learned.

Sources connected with the former couple tell us ... they actually split nearly 2 months ago, but kept it on the down low. We're told the breakup was civil. They're still friendly but simply grew apart.

We're told the breakup had nothing to do with recent stories of Casper's sexual escapades. One source put it this way: "Casper has been a single guy and can text or see whoever he wants, but the idea that he was knowingly texting a transsexual is laughable." The source added, "He's not that guy, but like a lot of single guys online he obviously likes to look at a 'lil T and A."

Casper is in the process of moving out right now. We're told there was no rush because JLo's been on the road promoting her 10th album, AKA.

We're told Casper will be pursuing acting, which is why he took show directing and choreography off his Instagram.

Jennifer Lopez must sure think Casper Smart is cute, because upstairs there's a vacancy -- he just ruined her big announcement that she's returning to "American Idol."

Smart was promoting his new show -- yes, anyone can -- when he was asked if his GF was coming back to the struggling show. He dug deep and said, "Yes."

Apparently Casper thought the cat was already out of the bag.

Casper Smart is like a gremlin ... whatever you do, DON'T GET HIM WET!

With the rain coming down pretty hard in NYC on Wednesday, J.Lo's boy toy was safely sheltered from the elements with TWICE the amount of umbrella assistants as Jennifer.

Marc Anthony and his kids hit up Disneyland with his new girlfriend who is both hot and billionaire-adjacent.

The new GF is Chloe Green, daughter of UK billionaire Sir Philip Green, whose estimated net worth is $5 billion.

It's a good bet Sir Philip provides his daughter with an endless supply of loot. He reportedly dropped $6 million on his son's Bar Mitzvah -- a lot more impressive than a bunch of useless savings bonds.

Marc Anthony isn't just on good terms with his estranged wife Jennifer Lopez ... he's also on good terms with the guy who's bangin' her ... at least judging by this photo.

TMZ has obtained a photo of Casper Smart in a great, big bro hug with Marc at a private airport in NY yesterday.

We're told the kids -- Emme and Max -- have been hangin' with J.Lo and Casper during the most recent leg of Jenny's international tour ... and when they arrived back in the States on Monday, daddy was right there to greet them.

Marc Anthony held out hope for a reconciliation with Jennifer Lopez, but decided to file for divorce when she told him ... she's madly in love with BF Casper Smart ... TMZ has learned.

TMZ broke the story ... Marc filed for divorce Monday -- nine months after the couple announced they were splitting.

But sources extremely close to Marc tell us, he didn't make the decision on his own -- he had a heart-to-heart with J.Lo a few weeks back to see if she really, truly wanted to end the marriage.

We're told he said he wanted to give the marriage another try, but Jennifer confessed ... she was deeply in love with Casper ... and wanted to pursue that relationship.

We're told Marc was blindsided ... he had not idea things were so serious -- and he was hurt.

Jennifer Lopez is drawing a line in the sand -- paying nearly a grand to rent out a public beach in L.A. last weekend ... to keep randoms away from her family and children.

Sources tell TMZ, Jennifer forked over $925 to the city of Long Beach to rent out Marine Beach on Saturday -- 3,400 feet of shoreline -- just for her, her kids, her BF Casper Smart and other family and friends.

To keep out the riffraff, we're told lifeguards marked off the water using buoys -- and kept the beach gates locked.

We're told J.Lo and co. brought their own jet skis for awesome fun times -- and even hired a wakeboard instructor.

Jennifer Lopez and her 24-year-old boyfriend Casper Smart were quite the lovebirds and enjoyed a Valentine's Day frolicking on the sand in Santa Barbara on Tuesday.

Besides holding hands and taking long walks on the beach, Jen even climbed up on top of Casper to ride the swing together.

Jennifer Lopez showed off her 42-year-old mother of two taut flat stomach while in Malibu the other day.

The "American Idol" judge was looking belly good, as her 24-year-old boy toy lover Casper Smart frolicked on the sand with her daughter Emme.

Jennifer Lopez might want to think twice about handing Casper Smart the keys to her Bentley ... 'cause her BF just pleaded no contest in a drag racing case.

Casper's high speed bust came back in April 2010 -- long before his J.Lo days -- and today an LA County Superior Court judge hit him with 12 months probation and a $500 fine.