AITA for not apologising to my sister-in-law?

I (28M) have been married to my wife Emma (28F) for a year. Now that we're married a lot of people are asking us about when we're going to have kids. We both have chronic mental and physical illnesses, that make it harder for us to care for a baby. Emma has been told by doctors that she could develop complications that can cause a miscarriage or stillbirth, or endanger her own life. Based on our experiences with depression I don't know if we would be able to cope, so we decided not to have kids. We've discussed potentially adopting an older child, but we're going to wait until we're in a better financial situation.

My sister-in-law Caitlin (29F) has been weird about this since she married my brother Dean (30M). She's always been dismissive or even passive-aggressive about our decision, but has gotten worse since she became pregnant. She has this idea that Emma should get pregnant too, and constantly messages both of us about babies and pregnancy. It makes us uncomfortable, but whenever we speak to her or Dean about it they just brush us off. We don't see them often, so we'd just decided to endure it.

We joined them for dinner at my parents' house last weekend and Caitlin spent the entire night talking about her pregnancy, and if anyone tried to change the subject she brought it back to babies. Normally we would have just ignored it, but she started going on at us again about having a child soon. Emma explained to her again why we are never going to have kids and she started screaming at Emma, calling her selfish for not wanting to have kids, saying she was less of a women for putting her life above potential children and accusing us of using our health problems as excuses. Emma was stunned and I was done with putting up with Caitlin's crap.

I started yelling at her about how she had no right to say that to Emma when she has never had to struggle with the things my wife has been through. I'll admit that some of the things I said were harsh, but Caitlin crossed a line with what she said. We left after that and both spent the night away from our phones just to deal with what happened.

The next day Dean demanded that I apologise to Caitlin for what I said. When I asked if she would apologise for what she said to Emma he dismissed it as her just being crabby from pregnancy hormones, and I had overreacted. I refused, as they clearly only care about their own feelings. My parents want us to apologise to each other, but say I should be the one to reach out, which I refuse to do. My sister Jenny (24F) is on my side, since she has also had to put up with Caitlin's crap. The rest of my family has gotten involved, and is putting pressure on us to apologise.

I refuse to let my wife be disrespected for her health issues, but the way my family and some friends have responded to the situation makes me wonder if I'm overreacting. I thought I would come here for advice, AITA for refusing to apologise?