will she or won't she?

My sister in law finally wrote to me, and said that she's leaving my brother because of what I said to her. I don't know what to think. I won't believe her until it really happens. And even then...I live 5000 miles from them, with no plans of going back, and I have no contact at all with anyone else in the family, so how will I ever know for sure if she's lying or not?