Help!

I've got a 4 month old baby girl, me and my partner just don't get on at the moment, he constantly lies, doesn't put any time or effort into our daughter, doesn't financially support her & smokes weed (even though he's told me he's stopped- he stinks and tastes of it) he doesn't spend any time with us & to top things off I've just found out I'm 5 weeks pregnant!!! I said I'd never consider abortion but right now I feel like it's the only option I have, I still live at home too and with my girl being so young I don't know how I'd cope with another, this one would literally be due around my daughters 1st birthday! just wanted people's opinions and advise!!

Btw- we've only had sex 3 times since my daughter and have used protection every time (condom split and I didn't realise)!!