Might be stupid, but I don’t think so!!

So my son is going to be two in April and his father walked out on us 60 days after he was born(I only know this because he spent 55 days in NICU and his dad left 5 days after) regardless....I got my own place, great job, amazing boyfriend and now all a sudden his dad wants to come into his life and be present...which I’m not against I’ve ensured that Titan (my son) knows who his “real” dad is and I’ve never dented his father from seeing him, but his dad told me he is dating someone and that’s fine...but I started doing my typical CSI stuff and come to find out she’s a druggy, has been fighting for custody of her child and what not, and I’m just in shock, it doesn’t surprise me that his father would be with someone like this. And I understand everyone has their demons...but his dad is basically arguing with me over the fact I don’t want a drug addict around my kid and he said “she’s in recovery” and i was like okay well when she’s no doing drugs for a YEAR she can meet my child...now he’s threatening me with taking me for custody and blah blah..

Am I wrong for not wanting her around my son? I know I’m not but I need opinions. I grew up with a druggy mom and that’s the last thing I want my son to witness.