Coping with the regret of taking them back

Does anyone have advice for coping with the extreme regret of letting yourself get hoovered and then suffering an even more brutal discard? I broke up with my ex a few years ago over “microcheating,” fell for a hoover nine months later, enjoyed a couple more years of idealization, and then recently faced a sudden discard with full-on cheating that’s left me traumatized. I hate that I could have prevented it all by just not letting him come back. The hoovers are so convincing though with their lovebombing and promises to change. Never again.