More or less I've had the same problem with you.I loved my boyfriend but I used to dream of my ex.The thing is,when we are blindly in love with a person,when we breathe and live for him/her they become more than a part of us.When something doesn't work out and we have to decide that life HAS to go on without them,we attempt to make new relationships,meet more people,try to fall in love again.The question is...is it really right?Even though we go on and fall deeply in love with new people,there's always a feeling in our subconscious that....something's missing.None will ever forget their first true love no matter what.The only thing we can do,however is go on and try to be as fine as possible. Even if you love your new girlfriend the figure of your ex exists in your subconscious and that's the reason you dream of her.If you know that there is no way that you can be together again,and if you really love your new girlfriend I suggest that you stay with her (the new one) so that none gets hurt.Hopefully time will help you forget both consciously and subconsciously.Unfortunately sometimes we have to take life as it is....