You are already free right now and the past is already dead. It is not so important than you should feel it but rather you need to know it for yourself. 
Feelings are always changing. It’s nice to feel free and light, but those feelings are just as transient as the feelings they have replaced. If we get into the habit of avoiding unpleasant feelings and making a goal out of the pleasant feelings, we run the risk of falling into another form of cyclic confusion. 
The past has already let go of you; it is dead. And you have already moved on from the past, because it is no longer here. But your thoughts about the past, the way you dwell on memory and relive those feelings, keeps a ghost-like presence of the past alive.