Why do I do it???

So, I went to my last school dance last night and I was looking around at all the couples dancing together and having fun, while I was wishing that could be me. Back in October, I discovered that I had a crush on my best friend but, he had a girlfriend at the time who was 2 years younger than us and I wasn’t worried because she was super clingy and i knew they weren’t going to last past Christmas (I know, I’m mean🤓). Then I got the best birthday present ever which was the fact that they broke up on my birthday which is like a week and a half before Christmas. So my feelings for him kind of grew and we started talking more. I know what you’re all thinking: Why didn’t you ask him out then? Well when it comes to me and dating it’s not that simple. I’ve never had a boyfriend. So, about a month and a half ago, one of my friends started going out with him (I never told her I liked him) and I was devastated that I didn’t try and make a move. I told my friends that I don’t like him anymore and I keep telling myself the same but, I don’t know if that’s the truth. I don’t want to tell them anything because I could ruin the bond my and my best friend have. The last thing I want for him is to be unhappy. My sister has brought to my attention that I put other peoples happiness before mine and I’m starting to realize that. I’ve myself that I was going to stop but, I don’t know how. Any advice???