Emotionally detaching

How do you emotionally detach from someone you genuinely care about my wife wants to have kids and I do not. But I love her. I have a vasectomy from a forced ex wife and my current wife wants me to reverse it or do a sperm donor or something to have a kid. She has a lot of health conditions that is concerning as hell to me. I had to bury my son as he passed away and those thoughts come straight to mind knowing the toll it takes on a woman’s body to have kids. So now divorce is in the talks. Things are civil but how do I go about this? I don’t want a divorce but I don’t want a kid. I’ve been involuntarily ripped away from my kids from my previous marriage as she ran off with another man, and forced my kids to call him dad. I pay buku bucks in child support for kids I don’t even get to have time with. And now this current wife thinks it’s easy to overcome the scarred damage I have in that sense. And the thoughts of burying another loved one. So now we are roll fill out divorce papers. I can’t stand watching her pack her stufff. It makes me feel like shit and like a horrible man. Again I don’t want a divorce. But I don’t want kids. I do not know her take on divorce but she is so set of wanting to have a kid. Now emotionally I have to imagine her, my best friend, with a whole other man to start a “family” our marriage is great with the exception of her insecurities and this whole kid thing. I need help. How does one do as I like to call it “turn off the light switch” literally every woman I’ve been with turns the love switch immediately off out of no where or if they don’t get what they want. How the hell is that even a thing?? Woman please tell me that. How do you all of a sudden not care for someone you “love” out of just thin air? So do I go back to being single and give her off to another random dude? I’m so lost and I’m so hurt. Sad. Idk what to do. How do I detach?