I told my DH, after 13 years of marriage, it was over 6 weeks ago. Lots of things but all built up to me just not really being in love anymore and lots of things about his attitude towards me that had worn that away... I didn't deal with it properly, I should have talked to him more, but he also ignored the niggling unhappiness too. We did counselling and I was surprised to find that he admitted to being unhappy for at least 5 years, which I had too, maybe more like 10. I get the bit about him being like his dad, we had both fallen into the tiles of his and my parents, I had become the nag, the martyr, doing everything for everyone, whilst he just barely spoke, barely responded to anything, didn't interact with the children or me. We still had fun. Still had wonderful memories, but they were few and far between. He didn't make me laugh, didn't light me up. I know it's not realistic to expect that and if you talk to dome married couples (I'm 42 as well) then it fades. But it had gone for me, I avoided sex, didn't enjoy it, wanted it over with. I thought it was just my age and had kind of settled to accepting it, whilst turning into a very lonely, very bitter woman. I knew really deep down it wasn't tight but I kept busy, always had a project on the go, always something to take my mind off it. But it got to the point when enough was enough.
It's horrible, I won't lie, that conversation was one of the hardest things I've ever done. But, a week later, after the worst week ever of him crying every night, shutting down, not talking to any of us, then he said thank you for me being brave enough to end it. I think if we'd gone to counselling before, maybe years before, then possibly there might have been a chance, but like you I was exhausted by the trying, constantly trying to make things better. I met someone through work and I'm ashamed to admit had an affair which put the nail in the coffin really. No excuse and very much so it's made everything more complicated, but just that very short time of feeling totally loved, feeling comfortable with someone and totally myself, made me realise just how bad things were.
It's all horrible right now as we are still living in the house, I'm hoping we will, in a couple of months, have some kind of plan of how we are moving forward. Some things have been better than I expected, we are amicable, although of course both sad.. he's not turned as nasty as I thought he would, but some things are worse, for example he's currently bring an ostrich and pretending as if nothings changed, but then getting sad when I bring it up again, which is frustrating and is having an effect on the kids.. The lockdown doesn't help, he won't go out or do anything for himself either. Daily exercise had been my escape!
I'd say do it a step at a time, look at what money you'd get, jobs you could manage, if you could stay in the house... It might not be as daunting as you think. I was paralysed by fear of where I would live, how I'd cope alone, but once I looked into the money etc, I realised I could manage and I felt nothing but relief.
One step at a time, you dont need to think about everything straight away. Maybe book some counselling, we had 6 sessions and although expensive, it did help him to come to terms with it all and the last 2 sessions we used to work out the separation.
Good luck. It's so scary, but the relief when you've made a decision... I continually over thought it, still do, but mainly I feel positive and excited about my future on my own.