I'm 1/2 way to becoming a single mom (20 weeks along) and have given much thought to the father not being in the picture. While my situation is different, I have to say that the safety of my child it paramount to any right the father/sperm donor has to be a part of it.
He's just talking trash about getting custody of the baby, or his aunt getting custody. He aparently thinks you don't have enough stress right now As long as you can provide for the child, and are providing a safe and loving home, you should be in good shape. I would check your state laws, but more importantly, I would advise any single mother-to-be to consult with a family law attorney before the baby is even born, just to know what exactly your rights are, but also to see what his rights are. I know money is tight for most of us, but check out local resources for discounted or free advice. Also, keep record of any email, im, or communication you receive from him. And don't tell him you've lawyered up, either. I would keep that info on the down-low, so you don't put him on the defensive. (or don't inspire him to do the same) And bring a trusted friend or family memeber to the initial appointment, since us preggy women tend to be a little bit forgetful, and it can be quite overwhelming.
As far as if you're doing the right thing? You've already made the right decision. You've been through the mill, but remember that a strong network of friends and family can be a better support system than a s@#t for a father. And a woman who can stand on her own two feet will do more to raise a smart independent child than one who keeps crawling back to a man who dosen't deserve either of them. Even if you have nobody, you have yourself. And your baby. Do your best (which you seem to be taking care of very well) to put him out of your life entirely. And remember..it takes one shot to be a father, biologically speaking, but it takes a whole lot more to be a daddy.
Sorry I'm so longwinded. I'm new. Wanted to put my 2 cents in, since I'm going it alone over here as well. I'm learning! But I know there are a lot of us who need some encouragement from time to time.
Good Luck!
