You have your own principles... the question you need to ask yourself... is if this person is worth breaking your own rules and principles.... Last week, I was so sure breaking up was the right thing to do.
I have a feeling you dont think this guy is worth it... but then again... you also feel you are getting old and this is your last chance on a long term relationship.
Forgiving is one thing... but breaking your own rules is another thing. There is always a trade off. You cant have both and that is why we make choices. Good luck to you.