I'm sorry you seem to be struggling, but the truth is, we are all in charge of our own lives, feelings and our personal contentment. No one else is in charge of that.
And people walk into our lives all the time -- most walk back out. You're going to discover the ones with meaning will stick around.
Relationships with guys -- you're young, and young guys are flaky. They will be flaky until they are into their 20's (most of them). It's the way of nature, so my advice about guys is -- enjoy relationships you have and realize they will last til they don't. Imagining your fairy tale wedding when you're 15 with a guy you might be dating is a fool's journey. It doesn't mean these are bad guys, it just means they are GUYS. Simple as that.
Mental abuse by your dad -- some parents are incredibly insecure and stressed out and this causes a problem relating to others. If your dad is mentally abusive toward you, he's not that great toward anyone else, either. Observe. My father was the same.... he had issues. His issues were about HIM, never about me. It's very true.
Being used for your kindness -- i don't really understand this, unless you're a push over. We have to set limits and boundaries in our lives. Do not let anyone use you. Friends will come and go, believe me. Just go with the flow.
EXPECTING things in return from people -- expectations are a set up for a huge let down. I expect nothing from anyone. I live my life, enjoy myself, i do social things, i practice kindness, i have a few friends i give presents to.... and after it's all said and done, i don't EXPECT anyone to do anything in return. If i want something, i do it for mysefl... whether it's material things, comfort or something else.
Being "nice" to people -- this is how we ought to behave. Believe me, i have known a few people in my life who are shitty regardless of how "nice" i am. It doesn't matter in the scheme of things. This goes back to expecting things from people... we can't. But it's a wonderful thing to be consistently decent to others. So do it. I do too. And i don't feel all put down if someone isn't nice to me... i just figure they are an idiot, and i go about my own life. It's THEIR problem, not yours. Believe me.
You seem to be focused on the negative and not the positive because i am absolutely certain there are positive things in your life. Practicing gratitude really helps us to see that. Practicing self love helps too and you can find information about these things on the internet.
take care of YOU, because in the scheme of life, no one else will.
You're going to make good friends over time, and probably find a guy you connect with someday. Meanwhile the rule is still the same "take care of YOU"