No, you’re definitely not overreacting: “I said I was not happy about it but what can I do.” You can do a lot! Make it very clear it’s crossed a red line of expectation.
I’m a mother of three. This level of disrespect and irresponsibility would be a deal-breaker for me.
I’m assuming (if not adoption etc) you’re recovering from a 9 month pregnancy and the birth of his child - and possibly bf too. It takes 6-12 months for your body to fully recover, even without complications.
He has two children to care for. A very young baby and a toddler. It’s his responsibility to care for his children. More so, when the mother is post-partum/bf. Most women are in this situation only a few times in their life, so it’s exceptional.
And he’s travelling thousands of miles away, so couldn’t be there for hours if one of you had a sudden health emergency.
And his family think that’s OK?? So that’s how he’s been brought up as a man? I have sons and think this is appalling.
I don’t say this at all lightly, but if he can’t understand any of this, nor his family, I’d be considering whether he’s worth being in a relationship with. What sort of a partner and father is he or will he be?
Make it clear he’s crossed a line of ignorance, insensitivity, disrespect and irresponsibility. If he insists on going, you have your answer. But focus on yourself and your baby and child for now, asking people who do love and care for you for help while he’s away. And then slowly start to consider/plan for your future.