When's a rebound, a rebound?

Coldhearted

It's been approximately 2 months since my three year relationship ended. I still love my ex tremendously. I knew I was "in love" with her and not because I was comfortable. I not sure she was "in love" with me but she says she still loves me when we talk on the phone! I'm trying to move on but it's hard to let go of her. There are times where I cry myself to sleep or wake up in the middle of the night with a cold sweat. There are so many things that we have done in the past that remind me of her. Well I've asked my best friend what to do about this and he told me to try start dating other girls. He says it helps to get your mind off your ex but he also says it backfires on you too. It all depends on how you deal with the situation. But I asked him,

"Would I be in a rebound relationship?" He said it wouldn't because casual encounters with other women isn't really a relationship. Just as long you don't get serious too quickly! Then you could call that a rebound. Anyway, when is a good time to start dating again. I feel I have to in order for me to move on but my heart and mind is still attached to my ex!! I really need help on this one!!!!