I don't know if you have any other options or not. For the meantime, try the Yahoo DBT class and other on-line resources. http://health.groups.yahoo.com/group/dbtclass/
PC also offers a DBT class via chat on Saturdays that I have not yet been able to attend.
I don't see how the class could be designed for people like you, like us, if she constantly cuts you off. Cutting you off is showing that she doesn't care a bit about what you are saying; she is basically invalidating you before you can even open your mouth, and that's one of the main reasons most of us became BPD in the first place. Good luck.