That seems fine; take your time and figure out what you need to do to live with your own conscience. There's a difference between forgiving someone, and between letting them suck you back into their whirlpool. If you decide to accept Si as an acquaintance, I would keep it friendly and compassionate but light. Have firm boundaries in place that will not allow her to threaten your family again.
I am curious about how she will handle her future relationships with other people. I hope she has learned something from this one.
Love means never having to say, "Put down that meat cleaver!"