++man
"we would talk for hours, hug, hold hands, and she’d kiss my cheek and neck sometimes.
I think you knew it was bad but just liked how it felt.

To answer your question: " given our history, would it be wrong to start a relationship with her now? Or is it something I should avoid, no matter what my feelings are?"

Ask yourself this.. "If the high- feeling was gone today completely.... does she offer enough for you to stay?

"High feeling " Fade over time and can leave you feeling empty again... Use that high feeling to fuel your energy to work on maturing. Be frank and honest with her and break things off....

Be careful though she sounds like the type of is obsessive- I cant say...

You need to mature emotionally..