Eliminate the "shouldas" from your sewing life. Has a project descended into that abyss from which it shall never emerge? Write. It. Off. Don't let it hang around your sewing room like some Dickensian ghost. Give it away, cut it into quilt squares, mash it up for papermaking, hold an unfinished-object-swap with all your sewing friends, heck, throw it out or burn it if you have to -- I don't care what you do with it, but once you get to the point where thinking of it makes you feel guilty and self-flagellating, it is not a "unfinished project" but a curséd albatross. Sewing is no longer something people need to do to survive on the frontier [if you ARE on the frontier, pls ignore this part]; it's a FUN HOBBY. Vigorously expunge the parts that aren't fun. So you screwed up. So what? Bury the evidence, deny, deny, deny, and move ON.
Thanks A Dress A Day. You've just lifted about 6 weights off my shoulders. I'm off to start the bonfire now.