I’m finding it so difficult to get over my ex, I’m not sure what to do?

Last November my ex girlfriend ended our relationship due to a few problems. I was quite insecure and I pushed her away. We were only together for 10 months but it was very intense, we spoke a lot about the future, and she said how special it felt being with me (she used to cry tears about how lucky she felt). A few drunken arguments later and it was over. It was very amicable, and I get why she did it. We respect eachother. Unfortunately our friendship groups are tied, and they spend a lot of time together but I try and avoid social situations with her involved. In July, we found ourselves on a weekend away and after a few drinks we got together and cuddled all evening, sharing deep thoughts and being really intimate. The day after I said I’d give her space to decide what she wanted, and she ultimately told me she doesn't have the energy or head space to try again, but hopes we can remain friends. The day after this conversation, she showed up unannounced to my housemates birthday (they are part of the same friendship group). The day after I called and said it was insensitive to show up to my home like that, and she cried and apologised and said the last thing she wanted to do was hurt me. She also told me that breaking up with me “could be the biggest mistake she ever makes”, to which I scoffed and took it at face value. We agreed to distance ourselves. The problem is, her friends love me and theyre constantly inviting me out with them. They say that she wouldn't mind me being there which hurts even more. How can you go from being so in love to just being able to be friends. It’s a horrible feeling, and I just can’t seem to let go and get over it. I want to be able to go to social occasions with her, but I’m just worried she’ll do or say something she doesn’t mean. I feel awful telling my friends I can’t come to things as I think it makes me look weak and pathetic. I have done so much positive work on myself, but I just can't seem to let go. Help?

Updates
6 mo
I’m also dreading the day I see her with someone else and unfortunately I know that day will come. It’s eating away at me.
I’m finding it so difficult to get over my ex, I’m not sure what to do?
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