Accept my husband using drugs?!

Last night I found cocaine in my husbands wallet we have a 2 month old and we are barely making it with our payments, haven't even been able to buy Christmas gifts for the family but he can buy drugs right? Ok. So I call his sister who's is married to someone who does drugs and is 100% supportive of it and they have 2 kids and one on the way. Stupid. I tell her I want him out for that reason and she tells me I need to accept it and let it go. Umm what?! No! I'm not going to let him waste our money like that and be around my son while he's on drugs. She told me I was being selfish and that I can't kick him out because he cares and loves my son. If he did he wouldn't be doing dumb shit like that. Well, am I wrong in any of this?! Do I need to accept the fact that he's using drugs and wasting our little money that we have on his dumb crap?? We're living with my parents and he has that stuff here, disrespecting the fact that they have us living here for free. Well damn.