Do you know what went wrong last time? Did things move to fast? Did things fall back into the same routine?
As far as bringing up your issues, I struggle with that too. I have found that things do come up in time though. There have been a few times when my H was feeling comfortable around me and brought things up himself. Don't push it and don't try to get everything out at once. R talks are emotionally draining for both of you. It is a slow process. Be his friend and don't judge him. Make him feel comfortable talking to you.
I think MC is good for some situations, but not all. You would both definitely have to go into it honestly and with an open mind. I would say don't push the issue right now.
