He says he is trying to work on your marriage but he isn't?
When you say you haven't been a good wife, what did you do exactly? It sounds like you were abusive or you cheated on him.
I am trying but I believe this should be a group effort.
First you have to fix yourself before the group effort can begin. If you start the "group effort" too soon, you will likely forget to work on yourself.
Is he wanting her. Should I give him a way out? Should I bring him to marriage counsiling?
I don't know if he wants her. If you want the marriage to work you have to prove you are working on your self. Couples counseling might be helpful for you two, but you still need to work on yourself, and you might need single therapy also.
If you want the marriage to work, you have to fix yourself, and tell him you want it to work. And you have to earn his trust again. If you don't tell him, every week, that you want the marriage to work, then he will assume you are done with the marriage and he will go elsewhere.
I have a long time interest in psychology, specializing in relationship dynamics for 30 years.
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