Help Those with a failed SN attempt: What did you experience?

[homesoon.]

I have fully decided on using SN as my method, and I have gathered everything I could get my hands on for the attempt over the last year (though getting access to betablockers/meto would be great). So, really, I'm ready to go at any point once I can get over the last little bit of SI I have towards dying and the guilt of hurting my loved ones. But, I want to be prepared in the instance I failed.

For those who attempted with SN and it didn't work out, what did you experience physically? What happened after you realized you "made a mistake" or someone found you?