OP at some point when you are ready, you need to take the power back. And get some respect back. And face the fact that maybe the only way this will happen is if you leave him.
Start getting things ready. You need to be in a position to call time, and have a plan in place for how that will look. This will include getting details of both your incomes and pensions and assets etc. and speaking to a solicitor about how things should proceed.
I would start building up as much of a social life as you can. You have always seen H as your best friend but he isn’t acting like one now so it’s time to build up support elsewhere. You say H goes out quite a bit with this ‘group’ of people. Do you go out too?
I would not contact her if I was you. If she is indeed planning to leave her partner and ‘win’ over yours, you will just give her confidence that it’s working. You’ll also give them something to bond over - ‘his crazy wife’.
I would never ask him about the messages again. You know he’s prepared to lie to you over her, so it’s a waste of your time and energy. Plus you will now be too busy planning and building your own networks. Your silence on it will rattle him. Might even get bolder with it to provoke something. Just walk away from any traps with a sigh.
I would also, I am afraid to say, be a lot more grey rock with him. He is far too confident that you will always hang around for him. Far too assured of your devotion. He needs to start seeing things differently.
Any ‘emotional’ discussions will feed into his narrative. I would be cutting all of that dead. He says ‘You need better antidepressants’ or ‘Remind me what the rules are again’ and you say clearly ‘Don’t speak to me like that again’ / ‘I won’t be discussing this with you again’ and calmly leave the room. Any hint of disrespect from him and he gets the same answer. This aspect of grey rock is very satisfying. It sets new and clear expectations of how you will be engaged with.
It’s possible he will realise what he has to lose when he sees you pulling away. If not, then he’s already moving on and it was time to separate anyway.
Sorry this is shit OP. If you stay and carry on behaving in the same way, this will destroy you.
💐