They are really two separate issues. You can be completely “over” someone, but still feel beaten down, and betrayed. She didn’t have much empathy or concern for you. She probably loves being the center of attention and there are some people who thrive on the misfortune of others, or in this case, the comparison of others.
Constantly comparing oneself to others rarely does any good. People are different. They have different abilities, desires, and weaknesses. It is the self esteem of one’s own self that is the issue that makes people feel ok about themselves, or feel like crap. One’s own self esteem is way more important than what someone else says or thinks about us.
In this particular case, you could have been Superman, or The Pope, or cured cancer and halitosis and this woman would have tried to one up you. Some people do that, because it gives them a thrill.
You sort of allowed her to treat you poorly, not that you consciously did that, but it sounds like you have some self esteem issues and this woman was just the wrong person for you to be involved with. Next time you start to get involved with someone, figure out very quickly if they are one of these types of people who thrive on comparison and one upmanship. Ditch those people right away. I’m afraid you’re probably one of those people who give bad people lots of second, third and fourth chances, or you make excuses for their bad behavior. Don’t be that person any more. That doesn’t mean that you need to become an uncaring person, it means that you have to pay more attention to what people say and what they do. Also, try to look at things from the perspective of people that do care about you. If you mom, or your best friend or anybody that is close to you, who’s opinion you respect tells you that something seems fishy about so and so, believe them. Pay attention to what is being said, and how it is being said. Learn to spot emotional manipulation early on and don’t put up with it.
Here’s a primer on How to Spot Emotional Manipulation is a primer on How to Spot Emotional Manipulation
Because you are in such an emotional state, and feeling so down on yourself, I would suggest that some short term counseling is in order. A good counselor can give you the tools and support you need to be able to learn to deal with people like this woman, and to be able to conquer, or at least manage, your own self doubts, to put you in a place where you feel comfortable.
Since you have to see this woman at the conference, just go in there with the idea that you will be cordial and make your time as brief as possible with her. Don’t give in to any kinds of temptation that she might put you through (because she might. People like her are usually not done with people like you if they think they can get some more one-upmanship for their own pleasure). Try not to have to talk to her at all, but if you do, say something like, “Hello Karen, gotta run I’m meeting some folks for dinner/lunch/breakfast. Enjoy the conference.” Don’t let her engage you.