Most Helpful Guy
You are clearly not over your ex and I personally think your current SO deserves much better than this!
Try talking to a confidant or a therapist (if that's an option) and resolve some of your bottled up feelings from the past before continuing your current relationship.
If I were in your position, I'd go as far as to take a break from my current SO just so I can get my head on straight!
Best of luck with whatever you decide on!