Trying harder never works. I've literally fought for things, and tried as hard as I could to save friendships/relationships but it's always the other side lacking or giving up.
I'm done talking about that though. It's not my problem anymore, it's theirs.
My advice for you is to just mention that you're not feeling well, or ask if you can tell them something, before just coming out and saying it. If they say yes, try to keep it short. If they say no, don't mention it again. And if they did say yes, always ask before you talk to them about things again. Sometimes, they might be busy and not have time to listen. And when they say "Oh, you can talk to me about anything" don't take it seriously. That can change very quickly.
And if you lose friends, don't worry. It's their loss. It's not just you who has to try, it's them, too. She could have came and said "hey, what's up? how have you been?" but it was her choice not to.