Hi! Sounds like you're having a bad time. It's important to note that him entering a relationship, even as early as this one, doesn't say anything about you or about him, really. It's just life.

Getting into a rebound relationship isn't going to help you or fix anything. It's not even going to be a good distraction because you'll know why you got into in the first place.

But you don't have to be alone, either. Beyond friends/family/therapy (if that's an option) you can engage in something casual!

You can even enter into a relationship if you want, but you MUST be clear with the other person about where you're at emotionally, and consider the risk that it may end because of the way it started.

Hope that helps