I'm in a low place, and I don't know what to do.?

I think I'm depressed...and I don't mean it in an omg I'm so depressed way. I can't stop crying when I think about how alone I feel. My friends are all moving on, getting married, making new friends. And I'm accomplishing nothing. I feel like I'm invisible and alone. Even when people come over, I feel alone. I'm 21 (tomorrow's my birthday, so really I'm practically 22), I live alone, my best friend has made a new best friend. My dad wants nothing to do with me (he's got a new girlfriend who is 19, and apparently it's not cool for him to have a 22 year old daughter) my mom and sisters live about 25 minutes away from me, but when I see them, they don't see me...they just want to talk about their problems and I let them...they have no idea I'm feeling this way, and I'm pretty sure they would blow it off if I said anything. I have no money to go to a counselor, but I need some sort of help or I am going to do something I know I'll regret. I can't help but feel like my friends are abandoning me because I'm not as fun as I used to be because I'm in a slump all the time. Please help me and give me some advice... :( I don't know how much longer i can go on like this.