They turned abusive toward their existing children and the kids all got taken away. You don't like your guy's kid. The second mistake you made is dating someone who is in a vastly different life stage from yours. It got so much worse. Not necessarily NO desire, just that it wouldn't be a dealbreaker if I met someone fabulous and for whatever reason they couldn't or wouldn't be willing to have kids.
I think if you are going to date men with kids you need to be a bit more flexible, or don't date single dads.
This Is Why Women Really Don’t Want To Date Single Dads
I wake up every morning thinking "is this worth it? And find a women who isn't terrified of kids. I discovered here that a I am not evil and b this will not get better.