Ladies, do female dumpers get upset when dumpees move on?

My ex girlfriend dumped back in December and although it was amicable (she felt it was going anywhere and in all fairness, I took her for granted and never said "I love you" after almost a year of dating).

Anyway, after more than 2 months of no contact, we saw each other at event with mutual friends. The encounter was awkward, but cordial. However, a month later, she was completely cold and slightly rude to me. I later found out that she had been asking questions about my dating life and was convinced I was dating someone (I had in fact been on some casual dates, nothing serious and we are talking about 3 months after SHE dumped me!) Supposedly, she is not dating anyone.

I am not sure if she expected me to grovel for a second chance following our friendly post breakup encounter, or is simply upset that I started to bounce back. I hate to think that of someone I once cared for deeply.

Any ladies have perspective on this? If she was interested in reconciliation, should she not have made a move. I understand she is attractive, gets plenty of attention from guys, and I am supposed to be the "man", but still, I got dumped and I can't read minds!

Gents, please throw in any insight as well.

Thanks.
Updates
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I found out my ex will be at an event I will attend in a few weeks. Since she was cold to me the last time, I should ignore her. But, I don't want to be rude and stoop to that level. At the same time, I am tired being the one to approach with a hello. Will a simple nod suffice if we happen to make eye contact? It's going to be weird either way because there will be other girls there I will want to speak to (and I am sure my ex will speak to guys too), but I can't let my ex control outings.
Ladies, do female dumpers get upset when dumpees move on?
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