Hi Lone77, I'm sorry to read your story which is an all too familiar one in the MLC part of the forum. Your H certainly sounds to be in MLC from what you post. I wouldn't encourage you to file for D unless there is a financial/self & family protection need - this is a marriage saving site after all and you need to live with the decisions you make.
My scenario is pretty similar to yours - my H also has an ongoing A with a woman 16 years his junior and has turned his back on all that we had. He sees much less of his S (around once a month or so?) who used to live with us at weekends. It's sad to see and for now his world seems to revolve around OW and a new set of friends - doesn't have much to do with his own FOO or older friends - most of whom weren't keen on OW as she has a chequered history (previous A with another guy, cheated on him with H etc..)
I would encourage you to have a good read over on the MLC part of the forum and also browse around online for info about MLC. We aren't able to post links on the site, but there is plenty of information out there about MLC if you look around.
It's important to recognise that there's not much you can do for him or your M just now. The A needs to run it's course and that may well take some time. It sounds like your H is a 'clinger' in terms of contact. He feels confused and wants to touch base with you,but not to give OW up. He's trying to keep all options open. Watch out for cake-eating with that aspect and be clear about your own boundaries.
Good for you - you have recognised that doing things for yourself is the best way forward and it sounds as though you have started on that path. I would also encourage you to see a L and be clear about options and any protection measures that may be needed. Do look after your own interests as your H likely won't.
There are many parallels with your sitch and mine - but ours has been a shorter M (H's 2nd) and we don't have kids together - though I was very involved with my SS for 10+ years.
Chin up, keep reading and posting and take care. He may be self-destructing just now - doesn't mean that you have to.
Xx
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus