Hey Green Penguin and 

Glad you found the group; I know what it's like to be really needing advice and support when BPD might be in the mix.
How long have you and your H been together? Do you have any kids?
How long do his "rants" usually last? Do you typically stay there to listen to him "rant"?
It can be really helpful to have a T who is aware of BPD, regardless of whether the T "officially" diagnosed the person or not, because the core issue is behaviors, not necessarily a label. Is the T you guys are seeing a marriage/relationship therapist? Does your H seem to get along with the T (so far)?
These are not easy relationships so it's good that you're here, and that you have a personal therapist. Fill us in some more, whenever you get a chance--
kells76