something in the lines of “help me unearth and destroy [insert issue]”? You should really think about and formulate this on your own, But……
I don’t think this is a simple -petition-and-sit back-and-wait-for-it-to-be-resolved-kind of thing. It’s not asking for 50,= to pay back your roommate. This is getting to a deep-rooted issue and learning how to solve it’s unhealthy manifestation. You are going to have to do the dirty work yourself. Belial, when willing, would mainly show you how and perhaps lend you some strength. That’s how it worked for me at least, on a less severe issue than yours. If you are looking for a quicker and easier solution, I’d recommend doing a bunch of wealth magick to be able to afford professional help and medication.
To get you an idea and maybe some inspiration, this is the “short” version explaining how I’ve done this myself for my issue:
I’ve invoked Belial first. It took a few tries to fully become the essence of Belial in his aspect of Gatekeeper and when I was successful, as Belial/ part of Belial I’ve opened the gateway to my subconscious and it’s pathway to my issue. The intent used was focusing on opening the gates to my nightside and visualizing a pathway to that issue while recalling how being in that state feels like.
Using the Temple Of Ascending Flame sigil for Lord Belial as a gateway to that aspect of him worked really well for me.
After that I’ve done a bunch of dreamwork with and connecting to a collection of deities/ spirits like Melinoë, Hecate, Lucifer, Cernunnos, Nehalennia, Abaddon and Belial (pure personal choice that fit me, my issue and my progression. It doesn’t have to be this much or even any other entity, perhaps) to try to get them to help me unearth the links my subconscious had to my issue. That took a while and not all nights and works were successful. It took a lot of contemplating and being faced with my own negative aspects and weaknesses.
When I felt I got to the root/cause of it, it took a lot of fully experiencing the situation and the issue(s) that made my psyche go into that unhealthy state and expression. This was by far the most painful part of the process.
It then took a lot of attempts to destroy the connections my psyche made and let that part of my personality die (and I did actually let death-energy in to come as close as I could to the actual sense of dying). I’ve used Abaddon’s assistance for this in his aspect of The Destroyer. I think maybe Belial as the One without Master/ Breaker Of Chains might’ve at least be as good of an option, maybe better.
Simultaneous to destroying the connections your psyche makes in order to cope, I also tried to create different more healthy pathways to outlets that help me express/ destress
I also do not recommend to do this kind of work completely on your own for serious issues. It can be done on your own, but doing this kind of work is extremely uncomfortable and you have to be very, VERY careful not to fall back in the same patterns or even worse patterns than before. I’d recommend some sort of professional help to assist/ support you (maybe not tell them exactly how you work on getting to the bottom of your issue, if you don’t want to end up in a psych-ward 
) or a friend you trust and feel safe enough around (and is not afraid to call you on any BS when needed) to express to what you are struggling with.