Uma Thurman's Custody War Testimony, Toxic Relationship Hurting Child

Uma Thurman's relationship with her ex-fiance is so toxic they shouldn't be in the same room together with their daughter ... according to a court-ordered psychologist.

Uma and Arpad Busson were in court Friday for their custody war over 4-year-old Luna, and Dr. Sara Weiss testified about the exes, saying Luna genuinely enjoys her time with Arpad ... but definitely shouldn't go longer than 7 days away from Uma.

She said Luna shows signs of separation anxiety -- and Uma even had to come pick her up once, due to a particularly bad meltdown while she was with Arpad.

But the doc added family bonding shouldn't be part of the girl's routine. As she put it, "I don't think these two people should be in the same room with Luna."