Do I need to break up with my boyfriend of 5 years?

So I convinced my boyfriend, who's four years older than me, to make an instagram because he's so into art. I suggested lots of art pages that he does follow now, but did notice that he follows literally hundreds of instagram models and likes and saves a lot of their pictures. Our 2 years old was playing around with his tablet recently, and upon taking it from her, my eyes caught the words "she makes my heartbeat fast whenever she messages me" and of course, due to issues at the beginning of our relationship, I couldn't help but continue reading. The name was never mentioned but it was evident that he wasn't taking about me, but he was mentioning that he loves the person.

Shamefully so, I wound up reading the entire conversation, later noticing that he was talking to another woman. He was constantly bashing me to her, not once said anything good about me and told her a lot of my personal business. Things that should've stayed between the two of us. He also told her that he didn't believe that I actually miscarried our first child. He though I was lying. Mind you this happened 5 years ago. He watched me suffer day in and day out after I lost my baby. He also told her about his ex writing him on Facebook saying that she wanted to "serve him p*ssy for breakfast". I confronted him about all of this and he claims that he was lying about the ex writing him because he "just wanted a crazy story to tell".

The most pressing thing though, was that i put two and two together and assumed he was talking about another one of his exes when he was saying that he loved someone. It took some time, and I finally got the guts to ask him if he still loves his ex, who I knew by name. He admitted that he does, and my heart has been in pieces ever since. He was with her over 7 years ago and have been with other women since her and before me. And if that's not bad enough, as good of a guy as he is, he tends to have a really sucky attitude when it comes to me. I've told him could less times that I don't like the way he talks to me a lot of the time, but it just continues.

He apologizes but does the same things over again't and it almost makes me feel like he's manipulating me. I don't doubt that he loves me, but somehow I can't shake the feeling that he probably treats me this way because he'd rather be with his ex, that after all this time, he still can't seem to get over. He even told the female that he was talking to that I'm lucky that he's not like other guys because he would've "tossed me to the side by now". I've stayed quiet on things for so long but now that I'm no longer willing to do that, and that I'm standing up for myself, he badmouths me to so many people behind my back.

But I've stuck with him through everything that he's put me through. Yes, I know, I'M the idiot for that. I don't get it. I'm so good to him and I've only ever been respectful and good to him. I cook for him, clean for him, motivate him and support him, even when I disagree. Aside from financially, I practically have been caring for our child on my own since the beginning. All things that he doesn't do for me.

Sometimes I feel like I've fallen so far down the rabbit hole that I can't escape him, but I love him so much that it hurts. I don't know what to do and I've lost hope that things will improve. I want to leave him but I don't want to leave him. Probably because he's my first real relationship and we have a kid together. He even tells me that he wants another baby with me. How can I detach my heart from this and leave him? I know that I deserve much better than what he's been giving me, and no matter how much I bring it up, we always end up back to square one.