I want to ask my wife not to take a promotion
Why don't you want her to take the promotion?
If she does, she'll be away from home a lot more often.
It's good that you're voicing your concerns, since communication is healthy in a relationship. Just make sure those concerns aren't demands, as you don't have the right to tell her what to do. I hope you two can work out some sort of compromise!
It's like you are forcing me to become a single dad.
No, you don't have to agree to do all the child raising, but you can't demand anything of your wife. You should work to figure out an answer that works for everyone.