Depressed and thinking of suicide?

Alright guys, to start off i'd like to say this is going to be a little long, but i just hope to god someone can help me. I am a 19 year old male, just getting ready for highschool graduation (ended up staying back a year in sopre year) and recently I have fallen into a depressed/upset feeling stump. Ever since I was a little kid, my grandfather has been an alcoholic, urinating himself, soiling himself, and yes sometimes it has leaked onto the rug, and I had the misfortune of stepping in it. He is now 80 years old and the same thing occurs, we are going to look into isted living for him and my grandmother, so thats one thing that has been bothering me. Another thing is, I was with my girlfriend 2 years, I loved this girl more than words can ever explain, but I let my temper get the best of me, I ended up pushing her around/verbally abused her and she left me (I don't blame her) I guess you can say alot of my anger/frustration came from my home life and what I deal with, but i'm not making excuses, what's done is done, it was my fault. The thing that most affects me is I have severe OCD, and after my girlfriend left me I started hanging out with the wrong crowd, kids that use drugs, have been to jail, and once one of them came into my house and played video games with me, and now I feel I have sbag and prison germs all over my bedroom, and whenever I walk in my room I feel dirty because of this, I also want to cry because im very clean cut and I believe this has ruined my image and also im ashamed I brought those 2 kids into my moms house. Another thing that bothers me is when I was 15 I did a bit of recreational drug usage. Mostly acid, mushrooms, weed (alot of it) and that was it. Now I truly believe marijuana is a medicine more than anything, I dont drink or anything. But during this period I took a hit of crack, and that really brings me down. I only smoke weed about once every 2 months now. Im just VERY upset with my past and I'm ready to kill myself already because im sick of this ongoing headache. If ANYONE can take the time to touch up on some things and give some insight on any of my problems words cannot describe how much it would mean to me, I have no one to talk to, and I hate talk of antidepressant/psychs, drugs dont cure a problem, they cover it up. THANK YOU so much guys.. and I know I dont want to die, Im 19 and have (hopefully) a very successful life ahead of me - Eric.