DesertSun77, Welcome to our family!
I'm so sorry for the intense home situation that has led you here, but I am very glad you found us. There are many here who will be able to relate to you and help encourage you.
How did you first learn about BPD and come to suspect that your sister may have this? I think it is especially important that you are looking for support that will help you and your little one. You are both worth protecting and being cared for. Have you looked into any T for yourself beyond this site?
There are frequent arguments and she tells me almost everyday what I do wrong and how I have never supported her a day in my life.
Someone with BPD tends to be masterful at sharing FOG. Please know that you have done nothing to cause her unkind words. They are hurtful and painful. I can well remember the hurtful words my uBPDm freely shared with my siblings and I even now that I've become an adult. There are some good links to read under "Lessons" on the right side ---> which might be quite helpful to you.
You might be in need of one or two of these today.
Wools