For me quitting was as simple as deciding to quit and then promising my T I wouldn't do it anymore (I never lie or break a promise if I can help it). Now when the urges get bad I take a red marker and write words on my skin, which relieves a little and so far that's been enough.

Too bad you can't see a therapist at the moment. A therapist is someone you can be honest with - and it sounds like you don't really have someone like that at the moment.

Also something you can do is make a safety plan. You write down what you can do when the urges get bad. You can also make an agreement with yourself (for example) that you try at least 3 of the things in your safety plan for 15 minutes each and if you still have the urges, you're allowed to SI.

I hope you find something that helps you.