The good ones first.
My Mother Kyoko - NTR Fallen
A Wife and Mother The Aiden route. Doesn't go far yet, but that's AWAM for you.
These examples are pretty weak, tbh, but they're the closest things I can think of.
My Hunting Poorly written, art can be offputting, there's non-con and it's more friend/mom than bully/mom.
Taffy Tales Good artstyle, passable writing, it's more like friend/mom though.
Mother's Lesson : Mitsuko Ditto.
NTR Origins: Moreau Again, Naturally It's bang-on the theme, but limited to masturbation and only one scene, maybe the main game has more but I doubt it.
The Company Apparently you can have your mom work at your company and be seduced by John, who fits the bully role perfectly. But the game is so ****ed-up that you probably have to mind-break mom pretty hard to even get to that point. Might be wrong, though.
Reparations This is really scraping the bottom of the barrel. The art is actually fine, it's just that the writing is like a parody of the genre to the point of killing any enjoyment. Also I hope you don't mind rimming and giant lady-bush.