I was dating someone with a similar story (wife suicidal/was in the process of separation but separate rooms etc etc) The absences/lack of contact was always really well explained so I didn’t suspect.
One day, on FaceTime, I saw a flash of metal on his ring finger. I immediately asked what it was and the usual cool calm and collected exterior went to jelly. He lied and lied starting with the ring was for his dads benefit as he didn’t know they were separated and he had just been FaceTiming him - then moved on to he had just found it and wanted to brighten the day.
What worked to get to the truth, was calmly say that I wasn’t angry but we are both adults and I just need to know the truth. I reassured that I wouldn’t make any issues but deserved the truth if nothing else.
The actual truth was so much worse than I could ever have imagined, and it taught me more about what people are capable of, than anything up until then.
The complexity of the lie, the pre empting of things sometimes months in advance was simply breathtaking.
Id stay calm OP and ask for the truth now, as there’s clearly something not right, and then bow out with dignity and self respect.
I never did contact to his wife - I told him I would, so he did it himself. She contacted me, everything was blamed on me, but unsurprisingly, she was not suicidal/mentally unwell or any of the other descriptors he had used.
I feel for you OP, I’m still not over this deception, years later - he’s tried to contact me a few times ‘to say sorry’ needless to say I’ve ignored.
Good luck xx