Boundaries setting with friend gone bad?

[Dragonfly210]

Hello there-
I’m quite disappointed today. I’ve attempted to set boundaries with a very close girlfriend of mine. I’ve known her for over 20 years. 
I’m currently pregnant and going through IVF. The hormone medication is no joke and I can’t help but to go through the blues. 
My girlfriend and I talk about all types of things. We’re familiar with each other’s past. I come from an abusive home, which my Mother is a narcissist. I’ve had to endure physical and emotional and her selfish behavior my whole life. 
I’ve confided in her and told her stories of how my Mother would
Use to physical abuse me and would allow me to be happy with anything in my life. 
The other we were just texting and she’s been great. Checking up on me everyday. We were going back and forth then suddenly, she brings up how my Mom would abusive me when I was young. ?
Then, I responded quickly with, I’ve been working through this and processing the healing has been tough. I’m at peace with it and accept her for who she is.
I told her my Mother is an Orphan. I can’t expect too much from a women that never knew what it felt like to receive love from her parents or people in general. 
She didn’t stop. Then she told me. Well, there’s no excuse. ?
At that point I started crying and she had no idea. I told her, I don’t want to talk about this anymore. It’s making me very sad.
She apologized and said she’ll stop. 
Then, I got emotional and told her. I need to move on from his. I have a void I will never be able to fill and her being an orphan is the only I got. 
And requested for her to never bring it up again. 
She responded and apologized again. She said that we have often discussed our past and it was okay. I told her we’re older now, and would rather be honest with how I feel about things. She appreciated it had thanked me for being honest with her. 
That evening, we stop texting.
Next day, no text from her.
I know she’s upset. Probably because she felt this came from nowhere. 
The difference this time is, she brought up about my past. It’s usually me, that would bring it up. In other words, we would bring up our own stuff. Or, if she’s was in a negative space, I would try to be supportive and move her out of the negativity. 
I don’t know what happened to her this time. She just wanted to destroy my mother. I’ve never heard that from her before. Usually when I say, I’m at peace with it or I’ve accepted things for what they are. She’ll stop.

I’m sad because I don’t think she sees what she’s doing. 
Plus, why would you bring up stuff about the past to someone that’s pregnant and on hormones meds?!? 

I’m disappointed because I know she’s upset at me and thinks I over reacted. 

I do cherish my relationship with her and good friends are hard to find. But, there’s a line she shouldn’t cross. 

I don’t know what’s going to happen after this.

I’m sad because this will change the relationship. she has a history of being not being straightforward about how she feels about things. 

But, any perspective would be greatly appreciated.