i was the same as you plus suicidal depression. it wasn't nofap on its own but a combination of multiple lifestyle changes, but the core of it is to address dopamine deficiency. fasting is the fastest way to rebalance your brain but it's the hardest. unless you're seriously underweight or have a major health condition you can probably do a wet fast (water, black coffee and no sugar tea are ok) for 48-72 hours. typically by day 2 you begin to feel the mental health effects and by day 3 they amplify. once you finish your fast, go into a clean ketosis (lots of good meat, butter, olive oil, veg) and you will amplify the mood stabilization effects from the fast. carbs massively affect the gaba/glutamate ratio, making you more jittery, anxious, nervous, etc. when you are using ketones for fuel your gaba ratio improves and reduces your stress response. nofap also works as a multiplier here, and i found that when comparing the two, jerking off seemed to have more of an effect on anxiety levels and bad diet seemed to have more effect on depression levels, but ymmv.  once your anxiety improves you can start heading to gym, but there's nothing stopping you from doing basic calisthenics in your house rn (pushups, sit-ups etc.) when you start lifting properly this will also have a major stabilizing effect.  keep in mind that this is not some trick to "happiness", i'm still largely a miserable cunt but at least i can lead a normal life without having to get blackout drunk at social events or having panic attacks each time i leave the house. good luck.
United Kingdom