Help with getting anxiety over a man

I get severe anxiety when I catch feelings for a man. For some reason, I feel like crap all the time, even when they show interest in me, because I’m so worried that it won’t work out. In my head, we’re breaking up, before we even start dating! I go through all the worst scenarios thinking that there are so many, and there’s such a small chance of things going right. Even though we get along well and have things in common. Anyone else do this, and how can I stop feeling this way? It hinders my life and I just want to feel love without a side of crippling anxiety.