Him letting the woman move into the house with him without being married was his first mistake.
Him moving out of HIS house was his second big mistake.
Him staying in contact with the kid was not a great idea because well, women are evil often.
How much is it going to cost him to get the vile woman out of the house?
Is it more expensive than just walking away from the loan and telling the bank to have fun getting the house back from the whore?
Again, and it's likely my fault for getting too lengthy and not emphasizing the point from the get-go, I'm more so blown away of how a woman scorned was able to do so much damage and leave my buddy bleeding money to address it in the legal system than anything else.
That having been said- to clarify again, he bought the house (upgrading from the townhouse he had owned/lived in and using all equity he built) to purchasing the house specifically for the 3 of them to live in. Again, hindsight being what it is, at the time he thought this was going to be a marriage/future family type of situation and desired more space for this family growth than the townhouse he lived in provided. But- you aren't wrong.
As far as moving out being a mistake- that part I'm not so sure is as cut and dried. Remember both his name and her name is listed as the property owners (although his name is the only one on the loan). It very well may be different from one locality to the next but one thing I'm willing to bet as being universal is domestic situations are almost always "ugly".
On one end, there's my buddy that bought the house (again for the 3 of them) and is making all the payments etc. On the other side, there's the woman and her young child (and the woman is also on the title as a property owner). And for whatever reason she wanted him gone. I'm not the smartest cookie in this situation but my understanding, at least here, is someone needs to find another place to crash until the dust settles at least. My buddy (whose employment is dependent upon having a clean record & also was concerned about making a 'scene' I'll say for the child out of their best interests) did what he did. Right or wrong... I don't know but were I in the same situation... I at least understand the 'why' behind him doing what he did to de-escalate the situation at the time (hence the short-term apartment).
As for your 3rd point- again I can't find fault there at least on a high level. The more nuanced part though is my buddy had a strong relationship with the child and (apologies if I wasn't clear) it was the child that reached out to my buddy initially while this was going on. My buddy did reciprocate by answering the child/trying to reassure the child that everything is ok but that was used against him.
For the fourth question, the woman is out of the house (now) and he's back in it (lots of other drama there) but the problem is that she's still listed as a property owner. So he's got all that part going on while also trying to combat the PFI filed against him that has his world turned upside down from a firearm owner perspective (which is what I failed to emphasize initially).
As for your 5th and last question- IDK myself but I don't think he can 'walk away' from the house as being the sole person responsible on the loan to pay for it. I (personally) think his attention is best focused on seeing what the house had appreciated by since this all started and 'buying her out' based off of that but from what I've been told, she wants half of the equity to be bought out (as opposed to the appreciation) and that's where he's currently up to his neck in paying his lawyer to fight.
Hopefully that answered your questions/at least made sense.
-LD