Hey there, Lisa. Welcome! I completely understand the feeling of shame for failing yourself. My heart is with you.
If I may, I think it'd be a great idea to really reflect (and share, if you're comfortable doing so) what happened three nights ago. I think writing down a description of what your emotions were at the time you made the decision to engage in that drink, combined with knowing how negative you felt afterwards (perhaps another bit of writing if you'd like), would provide you an effective resource as you restart your sobriety. I wish you the best!