Thanks for the reply. This has made me think a bit and I've came to the conclusion that it's pretty complicated. I don't expect you read this whole long spiel as half of it is me trying to write it down in words for myself....

I think why it is continuing to this day is he started our relationship spending just as much time with her as he had when he was single. It didn't make sense to me that he was in love with her and had spent so much time with her because he wanted more (and was hoping for more) and then one day he finds out I like him too and suddenly over night those feelings just go out the window for her? Especially when he had been harboring feelings for her for years at that point and did not pull back on the amount of contact he had with her. I had wrongly assumed the amount of contact he'd have with her would taper off once he was dating me, but I never did until I told him it made me feel uncomfortable and we argued. Had he made the decision himself without getting angry and fighting with me over it, I think it'd bother me a lot less. It felt like he wanted to keep things the same with her, but also date me. It was impossible not to feel hurt as I knew he had never saw her as just a friend to begin with.

He admitted after we moved in together that yes, he was probably being inappropriate with how he handled the situation with her, but didn't seem to understand why it still bothers me to this day. It just feels really disrespectful and shitty for him to resume contact with her after all that has happened. Why is it so important to him to resume contact with someone he never saw as just a friend? Especially after he knows how he has handled this has made me uncomfortable and hurt me a lot. I guess because he's been willing to ignore how uncomfortable I have felt over her and still contact her in ways does make me feel like I don't 100% trust his intentions. Why is she important enough to him to continue to try and contact her through out our relationship even though he knows his contact with her hurts me a lot. I completely agree you can have friendships with people you were once interested in or even dated. But the way he handled it from the beginning has really set a negative undertone when it comes to her. I don't think he'd outright cheat, but his continued attempts to talk to her and the fact he never once saw her as just a friend and hung on to her out of being in love with her feels like he could be easily setting himself up for emotional cheating.

Is it okay to be "You've done some not so great things when it comes to her and you need to remove her from your life if you want to continue a relationship with me" or am I supposed to be "Okay, it's been several years, you can be friends" and suck it up. I feel like I can't be objective enough to know if something like what has happened can make it okay to expect he never resume contact/friendship with her (if he wants to be in a relationship with me). Or am I being too controlling and asking for too much? This is where my issue lies.