I feel torn......not sure what to do so need some help from you guys.....

Ok here is what happened......Last month my ss9 told his mother a lie about my BS8, my son got in big trouble for it when BM called and told DH about it, and I talked to BS8's dad about it and he was in trouble at both houses because we expect all the kids to show respect for each other and my son had not according to ss9...well when we finally got everyone together we found out that ss9 had lied to his mom and my DH. My DH came up with punishment.....to sit out at water park for 30 min while everyone else played and had fun...yeah right....well my DH ended up staying with ss9 and they talked and had fun for 30 min. not much of punishment...but I let it go. We tt ss9 next time this happened that he would not be playing football (starts 8/1) because that is a privilage you earn not just given to you.
SOOOOOOOOO, yesterday when DH picked ss9 up from summer program he told him a story that had happened to him that day...DH didnt say anything to me about it, and then while ss9 was on the phone with his BM he told her a totally different story...my DH looked at me and said that is not what he told me. So we asked him SS9 that is not the same story you told me....so what is the truth? he told the story..who the hell knows what is true at this point...But i told him he had to call his mom and tell her he lied again, he cried and carried on and stomach started to hurt. But he called mom talked with her and then DH said I want to talk to your mom..They talked for a few minutes and then she had a bad connection so she said she would call back. Well so no punishment, nothing really happened to ss9. So i sent DH a message this am and said..WTF? at what point is there a consequence to this?
He just called and told me he talked to the BM(bitch) this am and she wants us all to get together and have dinner and talk........he said well that includes Wife...she was silent for a few minutes and never really said anything. I said hell no to dinner...we are not a family, not going to do things together and that does not work....BUT i said we do all need to sit down together and talk... the more I think about it, The more I say NO..you guys talk about it. I have done everything in my power to try and make things good with BM and nothing works. I am tired of trying. I love my sk's but what do I do? Do I go so she knows I am not going any where or do i just let DH go and say screw it..your problem not mine?
I did tell DH that he needs to stick with what he says, you cant say no football and then forget about it...because then there is no consequence......