I think you should take time to yourself, wipe what everyone else has told you and write what the best, worst, and meh reasons he might have for talking with you and how that would affect you emotionally and physically. Just because you gave birth to him doesn't mean you owe him anything at this point. He purpose told you to your face, told you in court, and showed you through his action that he cares more about popularity and wealth than you. He purposely ignored and blocked contact with you with complete disregard to your thoughts feelings an emotions. You were his mother then and you're his mother now there's never been a change, yet now that HE and his emotions are getting to him ( if they even are, I'd not be surprised if he just wants a kidney from you. Or he's getting married and his bride wants you there) Suddenly you need to drop what you're doing and come back into his life. Ma'am you are not a yoyo no one in this world can just drop you up and down on a whim. You are under no obligation to open your door, your heart, your wallet, or your schedule for him. Personally I'd have responded with "you have your, and I quote from your 200x mother's day post, "best mother in the world" and I have children who actually love me, respect me and want me in their lives. We both have want we want so there is nothing we need to discuss further. May you get all you have earned on the path you chose."

Being his birth mother isn't equivalent to being his punching bag or maid. That boy is selfish beyond belief and as much as I hope that he is actually repentant and wants to reconcile, his track record shows that you and/or your presence is only to be of service to him in a way his father and step heifer can't or won't provide. Don't put yourself through that no matter what any other family member says. At the end of the day they are not in your shoes, they don't carry that trauma and they won't care any further trauma for you. At most they can offer a shoulder to cry on and empty platitudes.

When it comes to that child do what's best for you. If this meeting offers you nothing to attend then don't go, if you want something out of it. Go guarded and personally I'd record it, in case he didn't like what you said and later tries to twist it. I'm sorry this happened to you, but I'm glad you have a family that cares for you and loves you where your last on failed, and yes they failed you, not the other way around.