Im hurt, confused and just need to vent.

I've been with my boyfriend for 3 years now. Well like every relationship we have had our hard times. I think in the time we have had our relationship I've matured and come to realize what I do and don't want in a relationship. I let a lot slide with him but now I just can't anymore. He left for a job out of state for a few months 2 year ago. I was so heartbroken, the entire time I missed him so much, come to find out he was having an inappropriate relationship with a coworker and when he got back he hid that he was still talking to her. I was so devistated we had so many fights about it, I loved him so I let It go and he said that was it and would never happen again. In the time since than we have had issues and it hasn't been the same. He's immature. He's a bit self centered. It's always what he wants and when he comes to me he throws a fit. He'll stay on his phone at dinner he can barely hold a conversation or listen to my stories. I know he has ADHD but I can't keep using that as an excuse for his behavior. He won't talk to me for hours unless I reach out to him and its not even when he's busy. The only time he acts like he tries is when I pull away or I act really upset than all the sudden he tries and cares. Once I start acting myself again and doing everything for him he goes right back to his ways. He's just very emotionally neglectful. I would cry and say I miss him or can't wait to see him and he'd act like that was weird of me or I was too needy. He says he loves me and wants to be with me and would do anything for me but barely acts like it. We had some issues during a medically hard time for me about 6 months ago. After that I feel like something died in me. I just don't feel I care anymore. I don't feel the need to make the effort with him. He'll try to kiss me or have sex but I feels weird to me it doesn't feel like it used to and I feel like he's a stranger to me now. I feel horrible to have these feelings. I don't know what's wrong. I haven't wanted to leave because I feel bad and I'm so used to being with him. But I don't feel happy anymore. I told him he used to make me feel so good and he tried so hard and than at some point he got comfortable and lazy. He than said " well I was trying to get you and now I have you it's like fishing that hard part is over, ive caught you reeled you in and now your in my boat and I can know you aren't going anywhere" I guess that hurt me....I don't know I could vent forever on this. I just don't know what to do....