I still feel like her husband is a soldier that has been MIA or he has whatever profession and has been in a coma for a while. Mainly cause she still considers herself married and blames herself for cheating (which wouldn't really fit her personality if her husband just dropped her and ran off overseas or something) but she also still has hope that he might "come back", so she isn't a widow either. If I had to guess, then her getting confirmation of her husbands death or having to decide to pull the plug might be her breaking point. But I'm fairly sure the MCs line is to be taken as a hint that the fallout will destroy HER.
If he was in a coma, wouldn't she be visiting him in the hospital regularly?
What if he just left her for another woman, and she can't get over it? She refuses to move on because she wants him back, that is... until she meets the MC and his magical python.
She still wears her ring, keeps telling people she's a married woman, and keeps a locked room in her house... one that is probably full of her husband's belongings that he left behind. If you remember, Jill is familiar with her house, but was surprised that the door to that room was locked when the MC asked about it. So, I doubt that there's anything in there that is overly creepy. When we were first leaning about Bella, it was was fairly clear that she didn't trust men. She put the MC through the 3rd degree before finally approving of him. When she did "allow" Jill to date him, she got very irritable & angry with people. Maybe that was because she, herself, was developing feelings for him... but didn't know how to accept that.
In this latest update, after spending the night with the MC, she thinks to herself... "she's become what she hates, an adulteress." Why does she hate them? ...because one stole he husband away. However, she also tried to tell herself that her relationship with the MC is just "carnal urges", refusing to believe that she's falling for him... and the python. She's lying to herself.
I think her story is finding a way to come to accept what happened, and then moving on. However, I would assume that at some point... while she's well into her journey... her ex does come back. She will then be torn between letting him back into her life... or telling him to fuck off.