I agree with Theia. You have every right in the world to date and find someone that you enjoy - I just think that plunging in immediately after a long, confusing relationship would not be positive for you.
I advise taking some real time to yourself - I was always had a boyfriend from a young age, until my divorce - then had a looooooong time to myself, and found that not only do I do really well "alone", I actually like it! Who knew? And it's fantastic knowing that I don't "need" someone to feel complete. I have dated one person since divorce, and it didn't work out - I was very disappointed by this person's behavior, but was not sad to be single again. There just doesn't need to be a rush to date - maybe you feel like that since your ex is actively dating, but he doesn't necessarily sound like a model you want to follow. I think the kindest thing you can do for yourself is to give yourself true time and distance away from your ex, develop who you are on your own, and then, if you choose, find somebody. Independence is a great thing.