Apologizing now for the long post. It is a long story.

So in 2014 my ex (I will call him S) and I found out we were expecting a baby. We were 17 at the time. I had our baby girl in august 2015. We were engaged and everything. And by the end of 2016, we were in our own home. We broke up in December 2016 due to fighting and on Christmas Day I found out he was cheating and seeing another girl on his work breaks. The girl and I are cool now, because she was mature enough to call me and tell me everything that was going on and that she wasn't comfortable. Anyway, we've been separated since then. I have been seeing someone new (will call him D) since January. D and I are mainly friends with benefits because of our separate situations and I see him multiple times a week, without my child. He does not want to take S's spot and over step boundaries. Now S has a new girlfriend, who's already living with him. She's a total bum and is just disgusting and everyone besides S' immediate family members agree with me (his aunts, uncles, and even grandmother on his paternal side). She is 17 and I'm not comfortable with her around my child because she doesn't need to be there. 

Back to the point, I really care for D and he does with me as well and we say I love you and do all the relationship stuff a couple would do, just without a title and it's really irritating me because it's stuck at that point and probably will be forever. What would have been S and I's 3rd anniversary was June 4th and I spent all day crying. I tried talking to him and telling him I miss him a lot, and want to try to make this family work. He was at a loss for words but today he texted me and said no. I don't understand how he can't see even after all the bullshit he put me through I'm still willing to try again. I don't know how else I can convey that message. No one else would do this. And I know he knows that, and that his new girlfriend is him filling my void because she physically looks just like I did when we ended our relationship (overweight and disheveled). He tells me he misses the good times but not the fighting. Which I do too. But he doesn't understand that things can be fixed, he just needs to stop being thick headed and open up his mind. The thing that really gets me is when we first got together he begged me for months to date him. And I was nervous, and he told me to "just take a leap of faith". I always remind him of that. What I'm getting at with all of this is, my heart is conflicted. I really like D and have lots of fun with him but I don't want to keep having to have our thing a secret. And I really really hate S for what he did to me but I have harboring feelings and miss a lot about him and miss my little family being happy together. How can I get him to realize that I care about him and will put anything I have into making this work?