My stepson has a mother who constantly let's him down

Hello everyone, just joined in the hope of finding some advice.
My stepson is 10 and lives with his dad and me, he used to go stay at his birth mother's flat every weekend, just over a year ago we found out her boyfriend was convicted of possession of cannabis with intent to supply. We knew nothing about this from them.we stopped him going round there and she had to see him at a contact centre. That wasn't good enough for her so took us to court. The court decided the boyfriend wasn't allowed any contact with my stepson. So we had to let her have him every other weekend by order of the court but her boyfriend wasn't allowed to be there... She asked before Christmas if we could have him this weekend just gone, (12&13 Jan)as it was their anniversary and they wanted to go away. My stepson played up on Saturday and turns out it was because he is missing mummy, she last saw him boxing day morning. He won't see her until her weekend next which is the 27th Jan. We found out yesterday through Facebook (not because they told us) they went away and got married at Gretna Green! My partner is hopping mad. When is she planning on telling her 10 year old son she has got married? Advice needed please!

I understand what you want for him. Nothing but the best. And people like that are toxic in his life. I am in a similar situation also. A d my advice to you would be take it back to court if she married the man your stepson isn't suppose to be around then you and your husband have bigger grounds to get soul custody and her rights terminated. I wish you well. And you are the only mommy he needs. God bless you guys and good luck in your endeavors.

Thank you for your reply Momnaofa591
My only worry with taking it back to court would be the extra upheaval it would be for my stepson, he still cares about this man his mother has married, he still cares about his mother and while I feel she doesn't bring much to the table I think it would do him more harm than good if he isn't allowed to see his mother either.
I think we will continue to monitor the situation and take the lead from him. But I do appreciate you taking the trouble to reply. X