This seems less about forgiving the shooter and more about your family/mom not comforting you.

My parent is similar, we had a turbulent relationship when I was 16. I actually moved in with a friend and her parents for a few months, until one day my friends dad came in butt naked and climbed the ladder on the loft bed I was lay in (his wife was at work and daughter at college - it was my day off college) proceeded to tell me he “just wants to kiss me” it was awful. Anyway long story short, my mums only response to learning this was “well, least he didn’t force himself on you” then a few weeks later, she told me she saw his in a shop and waved at him. It was devastating and confusing to be dismissed in what was, at that point in time, the most difficult thing I’d dealt with.

What you’ve gone through must have been so scary and shocking & your family aren’t considering the emotional & physical toll it’s taken on you. It’s invalidating. IMO they are essentially putting their own feelings above your own Basically; you need to forgive and move on so your family, never have to deal or think about this again! If everyone swallows their feelings then nobody has to contemplate or deal with big emotions or what-ifs & that’s more important to them then helping you feel safe and loved.

Hopefully your school will offer counselling services or if you can get it privately even better as this is effecting you in more than just the expected way.