So...
Just so I’m reading all of this correctly...
She cheated on him and had a drug problem, yet she has trust issues? You knowingly and willingly chose to get with a married woman with several children from another man?
Then, you have the gumption to get upset when he sends additional money to support HIS children? You have the audacity to complain that he (the father of these children) is upset with the custody arrangement?
“I just want this guy to go away”.
Really? You want him to go away? Okay... sounds like all he wants is his kids. Give him custody, and I’d be willing to bet he leaves you alone. Even better, this will allow you and your woman to work on your apparent trust issues.
You are being played.