Cannabis is relatively self-limiting and usually positively affects serotonergic depression (it might not help the apathetic, fatigued, sleeping dopaminergic subtype but it is pretty neutral).
Benzos are known to cause depression on their own in absence of any other stressors, so you've got to cut those out completely if possible or strictly use PRN for anxiety. I can attest that long term use of clonazepam, for example (years at the same dose) caused dysthymia.
Booze is the worst idea, juust to get a step ahead of you. It sounds like you want to fade out for awhile, and I get that, and have been there far too often for there to be a fair god.. but the things you might possibly do while having a real 'reactive depressive episode' -> something happened, you have a good reason to be depressed and it will self-resolve without medication but it is very hard on people.
Here's a rule of thumb from a family therapist that turned out to be 100% accurate for me. Getting over breakups takes six months plus one month for every year you were together.
So gird your loins, process the grief and be prepared the the shit to keep bothering you for months. When you come out the other side you will be reborn wiser; also STAY SINGLE while going through this, because it is not fair to another person when you are working through a mindfuck like this.