three strikes you're out...

when do you stop giving people multiple chances to be a part of your life? what determines someone's ability to get another chance? i have a decision to make. let someone back in my life who completely screwed up or not, if i do some would say that i'm foolish. my head is telling me that after multiple chances i will be screwed over again. my heart tells me that another chance is worth it. my intuition is telling me this person needs something from me and that's the only reason they want to work things out. which one should i listen to: heart, head, intuition? its a tough decision...