I think replacing someone to get over them is possibly the least healthy way to do it, personally.
*thinks* I think that relationships, a lot of times, are like - hrm, sillyputty/playdoh on the emotional level.
The longer you are in one, the more you are 'shaped' simply via the pressure of the relationship, to fit into it better. Now, once you break up, you are still partially shaped by that ex.
To attempt to heal yourself by squishing someone else into that space just leaves you with 'gaps' between who you actually are, who you want/need to be, and who you should be in order to be best in a relationship.
You have to give your sillyputty a chance to 'reset' - to recover to it's 'neutral' and most 'you' presence, before you try to bring someone new into your life and start 'reshaping' yourself for the next.
And, the interesting thing is that - even if you aren't 'physically' still connected to that person, if you are still emotionally/mentally bound up with them - your sillyputty is not going to be able to regain it's 'proper' shape - it's going to still be pressured and shaped by the emotional and mental pressures of the relationship (even if it's one sided) that you still have with the person. You've got to let it all go - or at least push it far enough away to give yourself time to reshape and heal.
G'luck.