Am I right in being upset with my gf

About a month ago my gf (25f) went to clubbing with her friends to celebrate her placements. She chose to go without me since I was out of town. She went there wearing clothes which were revealing. Before going she had sent me a photo, which I was okay with since I thought she will cover up in the club.

She later said she continued the revealing dress and she regretted it. She also mentioned that she and her friends were hit on in the club and were asked for their numbers. When I sat down and talked with her regarding this, she said this was the first time wearing such clothes and that she would only wear them next time when she’s with me.

I am upset about couple of things. Firstly she should not have gone to clubbing without me since she always insists on going to club/restaurant/dinner with me when her friends are along. She gets very upset if I don’t join she and her friends while going out. But this time she chose to go without me.

Secondly, she shouldn’t have wore such clothes. Later on she was shifting part of her blame. Saying she told her friends that they should have made her aware of the clothes. I don’t agree with that because she herself should have been aware of the situation.

I am feeling upset about the situation even though its a month since the incident. We couldn’t talk about this since she was unwell for last couple of weeks. But now I am rethinking the whole relationship and if I should break up with her.