Confused and feeling alone

Kelly
I've just found out I'm pregnant about 4 weeks! I'm absolutely terrified! 
Around a year ago the same thing happened but unfortunately it didn't result in a baby! 
The father is younger than me by 3 years he's still a teenager...we've been sleeping together for about a year and a half now nothing serious for him but I've fallen for him really badly! He's my best friend in the world even though he treats me like utter crap! He barely speaks to me only when he wants to hook up although I've been having a lot of family problems lately and he's been really supportive. He sleeps with other people though and he knows this really upsets me but he still does it and denies it...we're not actually together so I suppose he can do what he wants! 
My issue is that last time this happened I told him right away and he was so angry at me he told me to get rid of it and didn't speak to me for a very long time! He said a lot of very hurtful things and I spent basically 3 whole weeks in constant tears! I know that this time it will be the same situation...he doesn't want kids so he says even though he's amazing with children..and I know if I keep the baby he will probably hate me and never want to speak to me again...he treats me like crap and I know I shouldn't care about him but when you fall in love with someone you can't help the way you feel! 
I'm scared of being alone in this I know after my family get over the shock they'd be really supportive and I think the same about his family I think they'd come around although they'd probably see it how he does that I'm ruining his life...I'm worried all my friends will desert me and I don't think I could cope by myself...I'm really scared and upset and confused and I'd just like some advice...I can't tell anyone I know yet :/ 
What would you do if you were in a similar situation? 
Please don't tell me I'm stupid for getting myself into this situation i already know I should've been more careful but it's happened now :) 
Sorry for the super long post