Hi and welcome,
raji! 
I'm so sorry to hear of your situation and want you to know you are not alone. I think many of us have felt the same... angry, hurt, it's difficult to muster up compassion when we are in that state.
Your daughter is pregnant and you ask if it's advisable to go ahead with it. I had the same concern when my daughter became pregnant at 20. When she called to tell me, "I've been off drugs two months and I'm pregnant," I responded, "Are you

serious?" I made sure to let her know she had options and reminded her that she has trouble with her mental health, was it a good idea to bring a baby, and the stress that comes with raising a human being, into her already chaotic world? My words fell on deaf ears and I had to accept that I had no voice/vote in the matter..
I'm sorry you find yourself in this situation, it's not easy.
I encourage you to learn all you can about BPD and to keep posting here. We are all supporting each other as we travel similar journeys. A good place to start is the post pinned to the top of this board, HOW TO GET THE MOST OUT OF THIS SITE. My apologies for not providing a link, I've got no internet at the moment so I'm on my phone.
I'm sure others will be along shortly to welcome you. In the mean time, please share more of what's going on. It helps us to get a broader picture so we know how to best support and advise you.
Again,

~ OH