I definitely think it's a mode of self destruction. She's a mum and responsible for 2 kids, she can't go out on big benders, she can't get addicted to drugs, she can't get in loads of toxic dramatic relationships. She cant do any of the things that people in self destruct might normally do. Buying something unnecessey and getting yourself back into the emotional guilt and worry cycle of not having money is impulsive and is kind of mental self harm, its not liking yourself enough to not do that to yourself.
I'm not sure if I've explained that well at all but I know what I mean
I do actually really root for her and I hope she sorts it out.