Actually, the interaction with the old girlfriend is exactly what you need. Now you know that you'll be fine out there. Obviously this woman wants to pursue something with you. If you know there's no possibility of that then please don't string her along and hurt her. Still, you should continue the friendship. Get to know her better. In the end, a loyal ex-girlfriend widow that could turn out to be an amazing partner might outweigh a known cheating and cruel wife. At least you know you have options.
