I've been on an SSRI for a while now and my libido is completely diminished. In other words, I can't fap. Should I quit the medications and see what happens?
Ask your doctor, dude. There are more important things in life then fapping.
But who knows, maybe he'll/she'll find an alternative.
If your libido is diminished, you shouldn't desire to do that. How much do you really miss it? Do something that will bring more joy to you other than a temporary release.
Get off the internet, relax in the sun, go for a walk, meet people, etc. I find working at something I enjoy to bring my mood up far better than jacking ever could.
People often aren't aware that SSRIs tend to level off one's moods, not make instant-happy. You have to work to get to a level at which you feel that you don't need to use the medication as a crutch anymore. This all assumes you actually need the medication, and haven't been misdiagnosed either.
Quiting the brain candy immediately is very bad, and could make you feel worse than you ever did before or even go psychotic.
Schedule a meeting with your GP or PSY to talk about side effects. It may be embarrassing, but it's better than asking for advice from strangers on the internet. This is something that could radically alter the path of your entire life.