What do I do? Life is changing to fast for me!?

A year ago my step-dad moved to calefornia, he became homless and cheated on my mom. She forgave him and he broke up with that lady, he is still homeless. My real dad I could care less about his never care for me and my step-dad has been there but his childhood was horrable and he did drugs. So you can guess that was hard for me. Not long after my mom found out he cheated she got super depressed she was depressed for about a half a year. Again another hard thing to go threw. I'm not a very confedint person, infact I pretty much have NO confedents, but my band dirctor is making me play Saxophone all by my self, which for me is a NIGHTMARE. Again some thing hard for me. Plus school is stressing me out. And just yesterday I found out my mom is looking for a boyfriend, I don't want a new ''dad''. I just really can't take all this, what do I do?? Maybe give me a little help on how to handle each problem..