Ok, i've been where you have been 7 yrs dating and a few years engaged...and it sounds like you were dating my ex e.g. dependent etc. LOL
As for this new girl, i will go out on a limb and say that yes you are on the rebound no matter what you tell yourself...she is your rebound. My suggestion is to keep things extremely basic with her...dont be exclusive. Date, see what you've been missing for the past 13 yrs and if things are meant to be with you and this young lady you will be together after you've slooted yourself around.
My loving wife is my best friend, mother to my kids and totally knows my slooty past and i'm in a way glad that i did go through all that because i do appreciate what I have and am very thankful and grateful.
So a: date her but keep it open, be honest with her so that she doesnt end up being hurt AGAIN and carry that baggage onto the next poor soul
b: see other girls, if that requires you to be a sloot for a while so be it, just dont LIE be honest
c: lastly, which is important, take the time to be by yourself and do things that you wanted to do but couldnt.
Good luck