One of the most difficult decisions anyone has to make in their lives, is whether to let someone from the past enter your life again. If you do, every moment of their presence will remind you of their presence in your past. It's like always seeing them through a filter of the past. If you don't, you will regret not giving them and yourself a second chance.
To sum up, the problem here is that: The time is different, they are different, but you are still the same.