That is what the courts are for, have them sort out paternity and visitation. Keep it above board and civil. Be patient and calm so no one can accuse you of being anything but. You'll win people over faster that way. The last thing you need is to be misjudged as crazy or manipulative. It's hard, sometimes impossible to come back from a bad first impression. Even when you're coming from a good place.
That's what I was also worried about, but I don't want my son to just pop up out of the blue and they deny him
Tread lightly. I've seen this backfire horribly and make the father cut ties entirely. It is his family and your actions may be taken the wrong way. Try talking to him first about your concerns and ask for the best way to get to know his family. Let him feel like he's in control. If you do something without talking to him first he might feel you were being sneaky and it could hurt the trust between you. I wish you luck, this isn't easy and I hope it works out well!
I agree i grew up with a dad who was hardly ever around and when me and my Bro did visit him or any relatives from that side of family we always feel like unwanted intruders, they are strangers to us even our half sis is. I think you should contact the mother and at least give her the chance to be part of your babies life even if her son isn't that interested. But if she really doesn't want to be involved then at least you tried to do the best for your baby and no one can say different :)
Thanks for the advice (: now I feel much better
I would contact his mom. Just so she knows that you arent excludung her or isolating your baby from their family. Despite him being a jackass..... his family may not be. Every child deserves to know both sides of their family regardless if the man is there or not. But do not get too disappointed if she does not react the way you want. Reach out to her for your baby...if you get no love or response...keep it moving.