If you want to stay married to your spouse and also don't want to unilaterally deny them what works for them, maybe you could come up with an arrangement that is the least destabilizing to you? My last girlfriend and I opened up the relationship about a year before we split, mainly because I'd gotten so depressed that I wasn't really present any more and was basically fine with it, though we decided to start with less-preferred-gender partners (we're both toward the straight side of bi). But I decided I didn't really want to hear about it, she went and found a FWB and we settled, with a bit of communication, on a don't ask don't tell situation. That was fine with me 98% of the time.

Amusingly enough, when my life finally did hit the core meltdown stage, this person - now my ex - was the one who gave me a place to live. I'm still at her house now over a year later, and I could quite possibly be on the street if it wasn't for her. I'm grateful to have found someone who, while she doesn't really understand, was always able to put up with my bulls---.

It's funny how stuff works.

Lamictal seems to do nothing for me except make me need to take it in the morning to stop feeling weirdly mushy, but we've had so many bigger fish to fry with the meds that I'm still on it.