Hello there!!
I think that when it comes to
SH .. it might be better to tell her little by little at first, too. I know that's going to be some stretch.. most people normally don't tell the whole problem/issue in one go(though if you did, it would help her to help you even more ) so don't force yourself if you're uncomfortable or still kinda worried about it, because I know that the worry and the anxiety that comes from possibly doubting your action is also something else to worry about.
Most of all, it'll be better for you if you are able to replace your Self Harm with something happier that will help you explore what you have, as well as explore your feelings at the same time. I know that's not part of your question, but I just wanted to put in some advice that might help. There's plenty of things you could do in order to rant out your feelings, and these activities could even help you in the future, as well as remind yourself that you can make a change.
Things will get better! In case you want a hug or just need a friend to rant to , I'll always be around!