My ex accused me of cheating and being with another guy before the divirce, among other things. I was not with another, but I strongly suspected be already was...it's pure projection and putting blame and their issues onto another to alleviate their guilt. They are mentally ill-end of story, case closed!
While at marriage counseling before divirce e while we were trying to work things out, the moment after I told the counselor why I had called the police on my husband bc of his abuse, my then husband offers up a "you know, she had an abortion almost ten years ago and killed my child-I'm still not over that "...and you know sonething? Counselor bought it hook line and sinker-the abuse and alcoholism were no longer the focus-my exs healing from my choice to have an abortiin were. Yep. Classic bait and switch. Anyway, again, the why is just because they are mentally ill.