I don't really have any helpful advice, but wanted to acknowledge your pain and struggle. I hope the feeling will pass soon. I know it's hard to ignore, but maybe try to get intensely focused on a hobby, even for like 30minutes? reading, writing, art/craft, gardening, etc. Or maybe do some cleaning, like focus on cleaning out the fridge or something. Maybe the SH urge will lessen faster. I know, it's like you never know how long it's gonna last.
Just remember that there were/will be times that you DON'T feel it THIS strongly. I don't know why you SH, not my business, but even if you don't believe it, you don't deserve to be hurt and it won't ultimately help or fix anything.
Maybe draw a picture of yourself, even a stick figure lol, and with a pencil/pen SH the picture instead. Like a cathartic, but better way? Just a thought I had. The rubberband trick does not always work, I know, so maybe that. Maybe try writing on paper (even if you rip it up after) how bad the urge is and maybe why you want to? Or a big distraction like tv, one of your hobbies? Just throwing out ideas. They might be shit ideas.
I hope you feel better sooner, than later. I hope you don't SH but if you did/do, don't let that make you feel worse, just start anew.
I know it's hard when you are super, intensely upset. Feels like it'll never end and the pit is too deep. I hope you're able to find some comfort and relief. I'm sure your partner and kids love you, and others, so don't forget that you are a valid, worthy person and soul. 