Ex Love issues

Hey guys...Just so that this wouldn't be long, I'd put this entire thing in point form
- GF of 3yrs broke up due to long disntance Realationship (i'm in school)
- I came back for summer break and ended up spending marjority time with her.
- I sensed that this rel. could really work out so I took a semester break to work on it.
- during the period while we broke up i.e. while I was away, she fell in love with a co worker
- right now she's basically torn between the 2 of us
- she says she really sees a future for us but is basically afraid to hurt the other dude's feelings
- Right now we spend majority time with each other, i.e. 4 out of 7 days of the week we spend the entire day together
- Just some info about her n the next dude, she's had sexual realtions with him, and he too also loves her

My issue right now is how do i seal the deall I respect she has a new friend, and she really enjoys the relationshp. I however don't think that in order for out realtionship to move forward, she can be spending that amount of time with him. Tell me what you guys think and how i should move forward