Best friend "stole" our name.

Cas • LEO wife. Dogs > kids.
Has anyone dealt with a friend or family member "stealing" your hypothetical child's name? My husband has a naming tradition in his family, so he has known his future son's name since he was a kid; William John. And back in 2011 we agreed to call our hypothetical son "Liam" for short. 
That being said, my best friend is pregnant with baby #4 (the first three are all boys) and every time she goes through the naming process, she asks if my husband and I have any names picked out, and the answer is always the same; "William John, but we'll call him Liam."
Mid-June, before they found out the sex of the baby, I asked her if they'd decided on any names. "No, we haven't even started picking." A week later, she texted saying they settled on the name Liam Blake for a boy! I was pissed, but didn't want to rain on her parade so I simple stated I really hoped it would be a girl in that case, since John and I had agreed on Liam three years ago. All she said was, "Well shit lol." 
A few weeks later she called me after her latest ultrasound, "It's a boy! So you and John are going to have to find a different name. Or get pregnant really soon!" That last remark in particular hurt me because she knows the insecurities and fears I have about being a mother. Excuse me for choosing not to have four children by the age of 24. I have some shit I need to sort through before I bring a child into this world! 
Instead of lashing out and completely shitting all over what should be a happy moment for her, I just quietly shut it all down. I usually have pretty thick skin when it comes to her and her slights, but every couple of years she does something big like this, and I can't deal with it anymore. We didn't fight, but we haven't spoken since June despite having been best friends since we were 10. Has anyone encountered this situation before? How did you handle it, and what advice can you give me?