@Yellow. You are blatantly projecting.
Anyway, that aside, you made the point of FDH deserving being demonisation. I think that has been done pretty adequately on this thread actually! And yes, people are absolutely 'allowed' to leave unhappy relationships. They completely, totally and absolutely are. You speak about morals and yes, you're right. In an ideal world, the marriage would end before any heads being turned. Back here, in the real world, however, that doesn't happen very often. Particularly for men. New loves/lusts are the catalysts for marriages and relationships ending every day. Does it make it right? No. Can I personally do anything about that? No. I'm not sure why your pointing your cyber finger in my direction for stating the obvious. This is the actual situation. Ain't nothing I or you can do to change it. He's gone.
My post was unkind and unhelpful you say? Well, I completely disagree with you. Your closing advice to the OP was to 'keep on taking advice'. What you should have said was, only take advice that is dressed up with niceties. And again, as I've previously said, niceties have their place. The OP has had a terrible, terrible shock. However, no amount of 'you're a wonderwoman', and 'keep on goings' (one of your own) is going to help her longterm. That's the bit I'm interested in right now.
Longterm, she needs to protect her daughter from future daddy issues. She also needs to brace herself for future perceived 'betrayal' from her inlaws. I'm not going into it all again. I've made my views on that clear in previous posts. Additionally, she needs to protect herself financially. She's gotten some sterling advice on this thread about that. Nothing is guaranteed. She needs to do everything she can to ensure she is financially sound. That includes earning her own money. If she receives a settlement large enough to ensure she never has to work again, well happy fucking days! She's earned it. But what if she hasn't? No amount of 'poor yous' is going to pay the bills.
As for your little SAHM add on. I, personally, have no issue with SAHM's apart from the fact they leave themselves open to veritable shit storm if the marriage hits the fan. This thread is a point in fact.