The other day I saw her at a function with mutual friends. We made eye contact, but did not say hi to each other.
The last time I approached an ex in a spirit of maturity and friendliness, she was very cold and rude to me. I think that ex found out I was dating other girls. But, SHE was the one who broke up with me and told me we could still be friends. She obviously did not mean it.
In any event, that bad experience with the prior ex put a bad taste in my mouth, and now I feel it is best to ignore all exes, as rude and immature as that may seem.