Yes, do that.
And find out what the house is worth, too.
Been there too, in detail, and with three dependent kids.
Half a house value is better than none, when push comes to shove.
If you dont want to do anything, why not do as I did- go and see a solicitor (free half hour, so h wont know), and get an appointment with CAB.
I did this in July, even before the big 'reveal'. I didn't go to CAB but I did look online to see where I stood, and solicitor provided the bigger picture.
It did give me some confidence, and possibly made me react differently when I found yet more evidence in September.
I also bought a spy device recommended by some fool on Mn, but it was picked up immediately by Norton Antivirus, so a waste of time, and a nasty shock. And anyway, I see now it didnt matter. The thing is, you dont need to worry about that so much, the bigger issue is the way he treats you now and how you feel about that. The OW are a distraction from that.
I think a counsellor may help you to think all this through, and may also help you to turn a major muddle into an action plan, with steps to look at and find out about. It doesnt mean you have to make a decision yet.
You are in charge here, he hasnt got your brain, as evidence by the fact you have posted at all, or thought about this. (Thats why they are such pratt, they think they have - would add a smiley if I knew how!) .