Anxiety.

I've struggled with anxiety since I was about 15-- I'm 22 now. Although I have been on a citalopram for my anxiety for quite a few years now, I can't seem to make my anxiety about my relationship go away. We have been together for 2 years. We live together and we are soulmates and we both say we're the love of each other's lives. Everything is great. However, in the past, at about four months of dating, he did some shady things (didn't physically cheat, but definitely made me uneasy). Ever since then, I've had the worst anxiety about him finding someone else and I always get paranoid that he talking to other  girls even though I know he's not. Does anyone else struggle with anxiety? Can anyone help me get over these feelings?!