AITA for starting to date the woman from our threes*me after my relationship with my ex fell apart?

Soren:

Was I wrong for eventually dating the woman from the threes*me after my relationship with my ex had already completely fallen apart, or is my ex unfairly rewriting the timeline because she’s hurt and looking for someone to blame? And honestly, if you were in my position, would you feel guilty too even if nothing happened until months after the breakup, or would you see this as one of those messy situations where the truth still matters more than how bad it looks?