Looking after somone can bring up mixed feelings. On one hand, you love them and want the best for them. On the other hand, you can also feel tired and fed up.
When caring for someone with a MI, such as BPD, it's important to recognise that the behaviours are symptoms of the disorder, not the person. Tough this boundary between the illness and person is very blurry. So try to put boundaries around behaviours that impact you the most.
You want to connect with @Che who has a daughter with undiagnosed BPD. She written about some of her diffculties here, and @Waterlily has similarly written here about her daughter who has BPD.
I'm sorry to hear about how this is impacting on you. Carers are at risk of developing their own MI too. I've written about the negative impacts associated with caring here. It's really important that you can look after yourself too. Reaching out on the Forums is good start. Do you get much time to yourself?