You can't trust him. Words are cheap. It's what he does that you have to go by. So long as he wants to be free to go for drinks with a female co-worker, he is not available to be in a commited relationship. This B.S. about how they are just friends is poppycock. He's shopping the singles' market. He wants to have his cake and eat it too. He's doing to you what he did to his ex. He'll be all yours, except when there's a chance to sample something else. He just needs a young woman dumb enough to put up with that. You don't have to.

Being separated from him will hurt. That's just how it is. Despite what he may tell you, he's not going to change. This is who he is. A dream you had has been shattered. You probably won't feel better, until a few months after you cut him off completely. Until then, you'll be clinging to the hope that he'll decide to be different. He won't and he probably can't. You'll never trust him. You're just not that dumb.