Boyfriend's Ex- Need Advice

Lodym • ....
Just a heads up... It's a pretty long story.
So my boyfriend & I have been together since October of 2014. I was his this first person he had sex with & he was my first love (I had sex prior to him). We had a lot of problems in the beginning of our relationship. We dealt with them but they started getting worse. One of those problems was his ex. He has posted a picture of me with a lengthy message on Instagram. One of his exes commented heart eyes, he told me she was gay and that she thought I was pretty. It was sketchy to me that he still talked to her but because she was gay and she followed me, so I followed her & could see her post her girlfriend, I didn't mind too much. Then there was another comment with laughing emojis, I asked him who it was and he said it was his other ex, they had been on & off for 5 years. He also exposed that they were still friends and still talked. It was soooo sketchy to me, I kept questioning him like "Do you still have feelings for her?" "Does she still have feelings for you?" "You don't think it's weird that she commented that if you guys are just friends?" To all of those he answered no. He said he thought she was his first love but he was young & didn't know what love was, so technically I was his first love, he said he no longer had feelings for her, so I left it alone. 
I ended up ending things with him during the
end of April because we always talked about changing our ways but never went through with it. I wanted us to change, become better for each other then get back together. I didn't tell him the plans because I knew he would convince me to get back with him. Throughout the summer he still tried to get back with me, it got pretty nasty, he started to say I never loved him, that I played him & I cursed him out pretty bad because of it. We ended up not talking for a couple of weeks. 
Then.... I saw on snapchat that he was hanging around his ex. Calling her baby & stuff, I was so broken hearted, I cried for weeks. He told me he didn't have feelings for her & here he is with her. He flaunted that she was his first love, when he told me I was. Around the end of November, I found the card that he had gave me when we first started dating. Before we broke up he kept jokingly saying I lost it. So I sent him the picture jokingly wrote, "Told you I didn't lose it 😝" So we ended up having a long emotional conversation. He said he wanted us to be friends, & I said I wasn't going to be his grind of he was her friend. Which I know is a little extreme but I was still hurt about everything, even though me & him weren't together, but it still hurt to see him with someone he warned me he didn't have feelings for & call her, his first love when he told me she wasn't. So he agreed, then, I started having suspicions on that he actually went through with it. A couple weeks later I asked him if he was still friends with and he admittedly told me yes. Which threw me off because here you are again lying to me. We ended up getting back together after I was sure they didn't talk anymore. But come to find out she's still close with his family, I mean 5 years is a long time so I expect her to be but they haven't dated in a while so that must've meant she was still keeping in contact with her while me & him were together before, which explains why they were still friends. He swears he doesn't have feelings for her but you told me this before. I don't trust him, everyone feels like I should but I don't. If me & him ever take a break again, which some couples need sometimes, I can't trust that he won't go back to her. & everytime I'm around his family, I feel like I'm being compared to her. His aunt even told him that he should go back with her, I need advice I've put too much into this relationship and I'm scared of being hurt again.