You have an opportunity here to give him a taste of reality. Follow me on this:
Many WASs don't come to their senses until it's too late and the LBS has moved on into another relationship. Now, I'm NOT suggesting that you date or anything like that. BUT - it can be a kindness to give him a sense of what life might be like once you've moved on and give him a chance to respond NOW while it's not too late.
You have a good chance to do this because he's not living in the home but is coming and spending time there. Stage a few things to make him think - things that might look suspicious but that you can plausibly explain away.
Examples: Two used wine glasses left on the deck or porch.
Flowers - (roses - when he asks, they're "from a friend, no you don't know them")
New Victoria's Secret lingerie - leave it hanging to dry in the bathroom, leave the bag somewhere in the bedroom.
Go away for a weekend - when he asks where and with whom, tell him that's none of his business anymore. (I went to a local hotel and cried and laid by the pool - not the most fun but it was refreshing and I know my ex wondered what I was doing all weekend.)
I guarantee you, he will start to think that what's sauce for the gander is sauce for the goose. And right now he just wants you to be his comfortable Plan B while he goes off and explores other women.
Also - I'm glad you're seeing a lawyer, but even if you do mediation, you need someone who is YOUR lawyer to advise you, separate from the mediator. And meet with your financial advisor too to see what financial position you will be in if H retires early and divorces you.
