Question around seperation assets.

Location: Portland Oregon. I picked other civil matters because it may cross a couple different areas. My partners mother just sold her house and has proceeds from the sale. Legally she is supposed to split the proceeds with her ex according to a decree from around two years-ish ago. The reason they are seperated in the first place is because he did some unscrupulous things (i can provide some general details if it helps the argument) that put him in prison in the first place about 5 years ago. The question I have is does she have to split the proceeds down the middle, or can an argument be made that since she was paying the monthly mortgage cost on the house this whole time he's been in prison by herself with no income from him there should be a percentage line drawn? Also based on what he did to get himself there in the first place is there any option she could try to retain a lawyer and have some push back to avoid paying him at all?