I made a huge mistake. Please help.

I slept with one of my long time friends who I've always had a bit of a crush on. We were "talking" for a couple of months after it first happened, and hooking up when he would come from school. I found out that a few weeks after the last time we had hooked up he got a girlfriend. (Disclaimer: I do NOT know if he cheated on her with me, but I saw him texting her the last time we were together, and she met his family a few weeks after, so it seems pretty serious now) I probably did not have a right to say anything but I felt disrespected as a friend. At that point, I told him I would have appreciated if he was honest with me and I later apologized for making it my business.All was good until last week when I went psycho since I was still hurt and made a fake Instagram and commented some very mean things on his new girlfriends pictures. I thought enough time had passed that he would not have known it was me but he and his girlfriend blocked me on everything a few days later. I feel SO awful. I don't know why I acted so crazy, childish, and out of character over such a short lived fling. I can't sleep at night my heart feels so heavy that I did this to him and lost a good friend. I am dreading seeing him or his family ever again and am humiliated. I definitely crossed the line, and I feel there's no redeeming myself.

I opened up to my mom, who asked me to not fess up and apologize which I would have liked to done (She is close with his mother, and I guess did not want to have problems.) So, I made a snapchat account under his ex girlfriends name and added his new girlfriend who snapchatted me (thinking it was his ex) saying "Heres my number if you have something to say." I said "I think I've said all I needed to, thanks." I know I now digged myself into a deeper hole, but I'm so embarrassed and ashamed of my actions this is something I never want to admit to. Im too deep in this lie to apologize now, but also feeling so sad and guilty. Any advice?