Have you tried the fifteen minute game? You choose to or not to hurt yourself just for 15 minutes. Then you occupy yourself with something distracting, at the end of 15 mins choose again, it's always up to you. The feelings always reduce eventually. The worker who helps me with my battle not to SI says it takes 1 to 1.5 hours for anxiety or stress to reduce. Sounds like forever, but it's only 4 'games' or 6. This helps me a lot.
i wish you well and send as much care as I can.
((((((((Catlover21))))))))

Ps congratulations on avoiding SI for so long, whatever you do (or have done since writing this!