Fiance's Stepsister

So I lost my baby May 27 at 8 weeks. My parents bought me a onesie after we found out I was pregnant and it was like a little baseball uniform. I put it in a shadowbox with my ultrasound and the name we picked out. I know it was early and never found out the sex, but we had this gut instinct it was going to be a boy. I posted a picture of the shadowbox i made and my fiancé's stepsister messaged me this. I have maybe met her a total of 4 times at the most and never had an actual conversation with this girl. Is it wrong of me to be overreacting right now? This really upset me. I am the one coping with my child's death, I think I should be able to think it was a boy if I feel it?

*Update*

This is the shadowbox that I made. I just wanted to share with everyone.