I had MANY day ones. Towards the end, I felt defeated. UNTIL, I had a last day one. I was miserable physically and mentally on that day, but paradoxically I also was hopeful, because I knew it was going to be the last.
That thought can be liberating, and freeing. So as you say, make this the last day one. You can do it. Put the scaffolding in place to put an end to this. (Post here, meetings, make a recovery plan, seek outside help, etc.)
What you tried in the past hasn't worked, so try something new. Hang in there, and know that we are here. Again, you can do this.