Am I Stupidly In Love or Just A Mug?

So I've been with my partner for 8 years, we have a kid together and we both have another child outside our relationship. When I met him his daughter was 3 years old, her mother had killed herself and he was raising her alone. 
So I've been helping him raise her since she was 3, she is 11 now - the same age as my daughter and we have a 3 year old son together.
Our relationship has not been the easiest - soon after getting with him I found out he was cheating on me - like a fool I forgave him and then she had his baby.
When I was pregnant with our son, the same girl was also pregnant with his son😐 I know I know I should of left, but I was so in love with him and believed his sorrys that I forgave him again - if I'm honest now I think I just didn't want him to be with the other girl that's why I kept forgiving him - silly I no.
Another girl was claiming she was pregnant by him, but she did a DNA and he WASNT the father - after that we broke up. I had enough. I mean even though he wasn't the father - he still cheated right?
He has constantly been messaging me and calling me telling me how sorry he is for the last 6 months and I feel like I'm on the verge of forgiving him again.
I know I sound silly but I can't help but love this man - yes he cheats and creates kids outside our relationship - but I love him.
Today I found out the other girl is pregnant again, he swears he's not the father but my mind is telling me something else and I just don't know what to do.
I asked her if he's the father and she hung up the phone on me and won't reply to any of my messages and he keeps saying it isn't his and I should take his word for it.
He did tell me straight away about the other two kids, but then I've also told him, if he hurts me again - I'm gone for good and I think he knows I'm serious, so maybe he's scared to tell me the truth I don't know - we haven't had sex in 6 months , so he could be getting it elsewhere- but I just don't know what to do 
Apologises for the long post 🙈
Oh and today he told me he wants us to get married he didn't propose but I guess maybe he's serious and wants to settle down or he's scared I don't know?