Need help with this... Please

Okay so I been talking to guy that I really like and found out he has kids, it's bit messy he hates her they been broken up for a long time now. Block her on everything but She doesn't want him seeing the kids but she a cheater and lair apparently who chills with wrong crew like hooking up wise while he getting his life together and trying keep kids. I have ask questions that I'm worried about him going back to her, is she going get in between etc... Told me no and to not worry about anything.

Am I crazy on dating someone with kids? Should I be worry? I never done this before but he treats me very well and we do like each other. Help!!!