OMG. That must have been so scary. I'm so sorry that happened to you. It must have been terrifying.
I had a similar experience in Spain. A group of 8 men surrounded me at the beach and started groping me. I yelled for help and the lifeguard told me there was nothing he could do. I ran as fast as I could, but one of them managed to catch up and grabbed my foot, tripping me. I got back up and ran as fast as I could back to my dad who was sitting aways away. It was traumatic. It took a lot of therapy for me to get comfortable with men again. Like, two full years.
I would suggest talking to someone ASAP. This incident will stay in your mind for a long time. Thank god you weren't physically injured. I cannot express enough how sorry I am to hear this. There are a lot of great women here on TPF to give you support!