Any advice on cutting ties with a family member?

[(: MrsSam :)]

So basically I posted a status on facebook stating how these past few weeks have been difficult for me and my husband. His truck broke down, we were left with one vehicle, and had bad news about the house we were buying. I talked about how I prayed so hard things would get better, and they did. I found out I was pregnant (something my mother has been stressing about for years) & how the mortgage company approved us for a loan. I also talked about how our child will have a home to call his/her own without moving like my husband and I did as kids.

Okay so my mom is never happy for me and is always talking down on me, had been since a child. She text me saying all this stuff about the status. How i said her and my dad "dragged" me everywhere as a kid. (obviously putting words in my mouth that i did not say) about how that status "hurt" her feelings. I tried stating she was being ridiculous and basicially read into it the wrong way. She told me to shut up and never to text her again.
So I didnt text her back, but she continued to argue.

What I dont understand is, why she cant be happy for me for once in my life. what do i need to do?? I really want to protect my child from her, because she can get so ridiculous and act so immature. What do i do?? All my life she's made me feel like i'm in the wrong with everything. I'm literally thinking of just cutting ties, because this happens ALL the time.