Is my ex joking about this to upset me? Or is the joke on him?

Just looking for other peoples opinions on this strange situation

Me and my ex broke up in September because I wanted kids and he didn’t, which is fair enough. We still slept together for around three weeks after we broke up which was silly really. He then went quiet on me and told me we shouldn’t be friends which I thought was really weird had he had wanted to keep the friendship. He then told me he was seeing someone else. I was broken by this as how can he have started seeing someone while sleeping with me and telling me loved me and was too heartbroken to start dating. We’ve had no contact since.

This month he tells a mutual friend of ours who is actually my best friend that his new girlfriend is pregnant, that she’s keeping it and that it’s great. Her facially reaction said it all to him, she was so shocked. He then said to her he was joking. Has he made this joke knowing that she would tell me? That seems so messed up.

I’ve been thinking about it more, and actually believe that she is pregnant and he was testing the waters and wanted to see her reaction. He has been adamant all his life that he does not want kids or the responsibility of them. All his work colleagues know we broke up because he didn’t want kids (I’m friends with his work colleagues) and all his close friends know that he has never wanted kids.

Either way, in this situation, he’s gone out of his way to try and upset me with a stupid joke (not sure why he would want to joke about something like this and include his gf in it) or she is actually pregnant and his life is now fucked, doesn’t matter if he says he’s happy about it or not, we all know deep down he’ll be absolutely livid.