Should I get out of this relationship while I can?

I have been dating someone recently. We have become quite close and it is obvious this is going to evolve into something more if it continues.

Last night I was speaking with this person, and he began to tell me how he had received an email from his ex girlfriend that he had broken up with, saying that she couldn’t be friends with him anymore. He said this upset him. He went on to say how she had asked for him back a few weeks ago but he said no because it “wasn’t what he wanted”. I asked him if he was “over” it and he said he didn’t know. He kept coming back to it “wasn’t what he really wanted”.

Anyway, I know I was beginning to develop feelings for this person. I told him that although I don’t have expectations for “whatever is between us”, I wasn’t willing to get involved in some kind of “love triangle” between him and his ex. He said he could understand that and assured me it was “over”. He has been messaging me most of the day acting rather depressed.

I am suppose to see this person tomorrow, but my head is telling me to get the hell away from this baggage. Should I cancel? My inclination is that I could easily become a rebound, which I definitely am not up for. I don’t want to be second best in this equation. It really is a shame because we have so much in common – I hate to walk away but I believe at this point he is showing too much care and thought about the “ex” for it to be worth my while.

So Flutherers, should I walk away before I am too emotionally invested in this person, or should I continue to see him and see how things progress? Is my pessimism acceptable in this circumstance?