Intrusive thoughts

I've had anxiety and depression for a few years now, I'm 22. It's usually one or the other. I've suffered intrusive thoughts before but haven't recently. Well, I've recently fell in love and I'm so happy with him. But every time he leave I have crushing anxiety. I can deal with that. But... Now it's intrusive thoughts as of yesterday I had one about him. My boyfriend. And I CANNOT COPE with it. I love him more than anything and I feel so guilty I could die. I cannot stop obsessing about having them and it's destroying me inside. I'll be okay for a minute and than I remember the thought I had. I'm so scared I'll keep having them and they'll never stop. What if I can't let go? I'm scared.