Okay, so at work, a co-worker hitting on you, period, is sexual harassment. We have a new piece that does a great job letting you know exactly what to do about it right here: https://www.scarleteen.com/article/abus ... _workplace
And just for the record, saying you are lesbian is not "provoking" harassment. His harassment is his doing and fault, not yours. However, moving forward, this person is clearly not someone you'll want to tell things to like you did. He's shown you he's not someone safe for you to share things like that with. I'd follow the advice in the piece above, and then I'd do all you can to get and stay away from this person. By all means, I'd not socialize with him in any way.
You're right, straight, cis guys can be super shitty about women who are unavailable to them. They, like so many people, can also be homophobic and misogynistic and this kind of stuff is very much a manifestation of both. And yes, both homophobia and misogyny are maddening, to say the least.
Suffice it to say, when we're not talking about a work situation, my best advice is just to shut down and get and stay away from men who act like this. They're showing you who they are and they're showing you that they're crummy people. I'm sorry you've had to take all of this in, it's really toxic and demoralizing.