Crush asked someone else out

I have/had/have this crush on a new friend at College. We’re not at all close but have always been chummy. I’m a few years older than him which threw me off when I caught feelings because I’ve never been interested in anyone younger than me before and he’s not at all my “usual type” but there was this tension that just built and turned into a full fledged crush.

I don’t know how to say this without sounding like an a-hole but I feel it’s relevant for context as well as the age difference, I do get told I am “intimidatingly attractive” often however really struggle with confidence issues and depression. He struggles with his appearance but I think he’s very very cute.

He is an all round nice guy but I would find “nicer?” to me. Going out of his way to help me, seeking me out to say really nothing then forget what he was going to say and run off, stare at me with this intensity (not how a normal person makes eye contact, that eating you with their eyes eye contact) and eyes would move and stay on my mouth while I was talking, would move across a room to within an inch of me if I asked him anything even just in passing, brush up on me sometimes just grab me out of nowhere, walk right on me when we walked together so much that I couldn’t walk straight, tease me over silly things relentlessly, all of this for months and months before I really knew I’d caught feelings.

Anyway I’ve been going a bit crazy wondering what’s going on so reached out just to chat to test the waters and he immediately turned that into who I had feelings for. I let him know that it was him and he told me he has a new girlfriend and doesn’t want to ruin that which I would never come between I’ve been cheated on a lot so that has my upmost respect and she’s probably his own age or younger which is going to be better for him. But I’m super confused did I misread this completely or did he still like me but just picked her? I’m not really all that bothered about him now that I know he has or has had someone, if anything I’m a little icked out at him but I’m also scared to openly flirt like that again? I thought it was really intense and all this progress had been made, I’m just embarrassed with myself that it seemed like more.

I guess my question is did he even ever have these feelings for me, has anyone else experienced something similar or am I going insane?

My confidence is usually shocking and I’m one of those people that goes into everything assuming everyone hates them so it’s odd that I thought this person was actually falling for me to almost obsessing over me, only for them to ask out someone completely different and act like this was all one sided, when I think I only opened up because of how hard I thought he was flirting with me.