So, this is a really weird question even for me, but it has been drilling my mind for a few days and I don’t have anyone to ask it.

So I want to apologize to someone I don’t know that well for my behavior.
And I have to say that the thought of apologizing for my behavior back then kinda gives me chills, bc the anxiety I was dealing with back then was simply atrocious, I was actually medicated back then but still had a hard time. It’s really weird how you cannot talk about this sickness (anxiety disorder) to anyone or use it to excuse for your behavior, it’s just something you have to deal with alone, and never talk to, to anyone unless you want to be looked at as a weirdo.

Okay, so like one and a half years ago before all these pandemic started there was a girl who was friend with a lot of my uni friends.
I was never really close to her, and I barely even interacted with her, but everytime she approached my friends and me she would say hi to everyone and talked to them about random topics as a normal human being, but every time this happened, I moved away from the group a bit because I felt that I did not belong to them (actually I just walked a little behind them, alone). She even asked me once why I didn't greet her when she approached. She tried to approach me on several times, and just to be clear she wasn’t my friend by any means, she was just a classmate I often saw on my classes. The real reason of why I didn’t wanted her near me is because I knew damn well that I will end up falling in love with her (and that’s something I never really do), I’m not sure on how to explain it but I knew it and back at that time I had a lot of things to deal with and I was sure that I just can’t deal with more pain at that time (or maybe I just don’t allow myself to fall in love, idk). Now I see that what I did was wrong and that she may wanted to approach me as she did on a lot of occasions with me being super dry/shy an laconic.
Now all this was like one and a half years ago, and I haven’t talked to my friend or her bc the risk of the pandemic on my country hasn’t ended and I haven’t got the chance to see them again, but I know she still on a lot of my online classes. And I have changed a lot since then, I’ve been reading, working out, and eating good so I’m really proud of all the things I have done during this pandemic (but still struggling with loneliness, more than ever), and I saw her on Instagram and added her (she accepted my friend request but didn’t add me back), and I don’t know why but I want to hit her on with a dm and apologize for my behavior back then.

Am I going mad bc of the loneliness/anxiety I’m dealing with right now for wanting to do this and this would actually be like super weird? Or is it not that bad and I should do it? Bc this has been really drilling my mind lately, and I really don’t want to do something dumb that I will end up regretting, bc I don’t know if she would understand what that means to me, and if I will just came out like a weirdo.