You and I put ourselves down a lot regarding how we acted in our relationships. But there is a certain dynamic to our relationships that cause actions and reactions. Don't be hard on yourself. I really get the idea that your ex would be like this with any one.
Also, one of the worst things to read about on these forums is when people reconciled with their spouses, only to have to go through betrayal twice. Ugh. It's heart breaking and doesn't ever seem to get easier. Sometimes I think it's a blessing in disguise when they don't come back.