I have BPD as well, but that doesn't mean I get to disregard mutual agreements and then hide underneath a veneer of "omg now I feel so bad because I hurt you please help me", because that isn't fair. I might feel that way in that moment, but that is my problem and mine alone.

Communicating feelings is fine, as long as there isn't an implicit expectation that you go and take care of her emotions for her.

She might have BPD, but I assume she's also an autonomous adult, right? As an autonomous adult she should be more than capable of following simple and clear agreements she consented to upholding. If the conversation went as you described I feel like you very clearly stated what you were and weren't okay with.