Whoa! Did not know that. That pretty much changes everything.

Yeah, let's just pretend that Debora Green and Andrea Yates never existed.

I also want to add that OP doesn't describe what the relationship was like BEFORE kids. Was she affectionate? Or aloof? Was she never a touchy feely person? Did she look forward to going on dates with OP? Did she ever initiate sex? Without knowing that, it's difficult to know how sharp a dropoff this is from her pre-baby personality.

"We’ve worked our asses off to earn a beautiful forever home" - sunk cost fallacy

"She walked away without saying a word." - post-partum depression

"We’ve had sex about 5 times within these 2 years and honestly, I basically had to beg for it." - you have lost pride in yourself and somehow accepted this as the new normal; its not

" I’ve suggested marriage counseling but she said absolutely not" - not acceptable unless she is suffering from severe depression

I would recommend getting as many family members together as possible, explain the situation to you, and then stage an intervention. If she still refuses counseling and an evaluation, you walk, and take everything with you that is due to you. I would also fight for as much custody as possible because I don't think someone like this is safe around children in the long term.