It has to be hard to really accept that ur child feels u failed them in some way .
And equally as hard for him to really look his mother in her face hold her accountable
You can tell he was stopping short of just flat out telling her how he really feels . He kept sugar coating it and going back to thanking her for how she helped fund his music career .
They need some sort of actual sessions with a mediator/licensed professional to provide a space where he can feel better just getting everything out without feeling a need to hide behind words of gratitude . and where momma dee can just really listen.
Im sure momma dee has her own stories and feelings about her parents as well that she may need to work through . These things tend to be generational