((( Silvia )))
First of all, Welcome to PC. We're glad you are here
You certainly do have your hands full with so many issues all balled into one it seems. I'm so sorry that your familly is fractured at the moment. I'm sure it seems like things are out of control right now.
I think it's important for all parties to have some time to absorb all the information and work through their emotions and feelings. I completely understand your husbands' feelings of hurt, anger and confusion. I completely understand where your feelings are lying right now. Time, patience and much love along with some possible family therapy might help to bring you both back onto the same page.
It's possible too that things won't work between you and your husband and you may have to work on finding a way to make it through without him. Putting your efforts into you and your sons is most important. I'm concerned that your oldest son is calling you names....it certainly sounds like he is hurting and needs some TLC and some clear direction with what is and is not acceptable to call his mother. Open dialoge with him (at the level he is able to understand) might be in order.
if the bio father of your youngest son all of a sudden realizes that he is liable for back child support and does not want to pay this, I would say you might have a good case back in court to stop the integration of the bio father with your son. I would strongly suggest speaking to a therapist regarding this along with an attorney. At the same time i have this gut reaction that the bio father of son #2 is playing games and needs to be held accountable for his actions.
This is certainly a difficult situation for all. I really hope that you go for the family therapy (including your children) regardless of anyone else. The three of you need to have some strength and togetherness between you in order for you all to move on productively.
Wishing you all well in this journey.

sabby