My step son wants to live with his mum

by Mich
(Northern Ireland)

My step son is 9 years old. He has lived with his father and myself for 6 years. In this time we have had 2 more children (girls). His mother gave him to us after a attempting to take an over dose, she had had many bad relationships and then took up with a man who didn't want children.

When my step son visited his mother her boyfriend would make him sit in his room, sometimes he was aggressive towards my step son and his mother. This relationship has now ended and my step son wants to live with his mother again.

He cries most of the time, nothing we do makes him happy and he resents his sisters. I don't know what to do or where to go for advice, I feel that if we don't make the right choices it could ruin his future.