He doesn't know I have bpd but I understand an important part of bpd is setting boundaries, but he gets off sexually on pushing people beyond their boundaries (think bdsm). 

I'm just a bit worried about this as I know that I'm a vulnerable person due to bpd and am not sure what I should do? Do I have reason to be concerned  even though he has made it clear that I can do only what I want when I trust him enough? Should I ask my psychiatrist what to do? 

Anyone have any insights for me?