Hi there. well, I don't think it means you still love someone or are supposed to be with them if you continue to have dreams about them after you break up. Dreams are our subconscious way of working things out. I dream about things/people and it's 'just a dream'. Now, you very well may have moved on too fast with another person. I agree to break it off. The problem with rebound relationships that happen soon after a break up or before we've fully healed is that we really aren't ABLE to be open to a new person. Comparing to the old guy, thinking of the old person, etc. are what so often happens and we blow it with the new person. Better to be on your own and heal.
If you wonder if he feels the same way, you can give it ONE shot. Contact him and say I'm thinking of you still and want to know how you feel. If he is happy with his new partner, then you must just move on. Take time to heal and don't date while healing. wishing you all the best. peace
Out of respect to this new person, you need to end the relationship or at least request a break. You need to figure out your feelings. Sounds like you may have gotten into this new relationship way too soon.