Think about what you want to dream about as you fall asleep:-)
magic amnesia dust
I never dreamed about your ex....so I really couldn't tell
I completely understand. Nightmares are nothing. Its when you are dreaming about something that you want and can't have anymore, everything is okay and how it used to be in your dream, but then you have to wake up to the cold hard reality! Its no fun. It will pass over time don't worry.
How long wereyou together?
10 years is a huge chunk of your life, I wouldn't expect you to have him out of your thoughts only 9 months later. It might take a couple years to get him out of your system, in fact you might always remember him, though im sure you won't be haunted by it as much as time passes. Thats life. We meet people, we take what we can from them and leave what we can't, and we move on. Memories are a bastard of a thing.