OP I understand where you are coming from. I am also very soon to be lone parent. Probably I already am. (x)H is has not come home today, guessing he is either looking for a flat to rent or with some newly met woman.
I have felt unloved for a very long time. He has been indifferent to me, would never ask how I feel, why I cry, has not talked to me for the last month or two, lived as in a hotel for a long time. It felt at times that it is a marriage of convenience for him, does not even care for his kids which is strange knowing that he cannot have any more kids and this is his only children. I can only attribute it to the guess that if he does not love the mother of the kids, i.e. me. I have thought that it is unhealthy relationship and very bad example of relationship for kids, for a very long time, but did not want to be the first to say that it looks like an end... The last trigger was just a week ago, I went to see my family, and he registered on numerous dating websites, commenting like his marriage has not worked out, it is a matter of time when he will resolve it etc. I told him that he has made the decision and I let him go. It is very painful and it is probably the right thing to do.
The worst part is that we have not talked for a long time, he refuses to talk and work it out. After I revealed that I know about his intention, he has not said a word, has not made the least effort to resolve anything. For me that means he does not care. Very very sad, but true - I have no other explanation...
Feel free to PM me. I was in this limbo for a very long time.