Er...yeah you can, you sit her down and say. I don't love you, this relationship fks me upl. I took you back because I felt bad.

Then you stop trying to be friends with her because that will hurt her a thousand times more than if you just walk away.
You cannot just slide into a friendship when these emotions are flying around.
I absolutely agree there is emotional blackmail going on, she is desperate, undulating at anything to make you stay.

Do the decent thing, be the stronger person and cut her loose and stop playing with her emotions. And before you say you aren't, you took her back when you didn't want her. So...

P.s yes some relationships can end in friendship, but not when there is this level of emotional instability going on, and an obvious issue with boundaries.