Fianc? (24M) made a comment that infuriates me (20F)

My fianc? and I have been together for nearly 2 years. We were having a conversation about children and how we both genuinely want them together. We have had the conversation many times before, but today, it made me aggravated.
He mentioned this time around that if were to be unable to bear any children, he would get a surrogate to have his kids. I was very uncomfortable and displeased with this.
Knowing how he felt about the reverse, I asked how he would feel I got a sperm donor if he were unable to produce. He claimed he would leave me. I was even more livid about this answer.
I haven't talked to him for a little bit since then because I know I would be unpleasant to talk to while this weighs my mind. I would like help in this situation. How should we proceed this conversation? I do not wish for us to impede on the other's boundaries. Thank you for any help you are able to offer.
TL;DR: Fianc? mentioned getting a surrogate, I disagree. I mentioned sperm donor, he said he would leave. How do we have a conversation about this (if possible.)
Update: I still need to talk to him, but I will say I am slightly more calm now especially realizing how surrogacy works. I am not sure if he knows if surrogacy works that way, which is why I'm sort of still iffy, but either way, I get it. Thank you guys for the support. I will still be talking to him soon.
Not Update 2, but a clarification (?): _______Thank you, genuinely. I understand how everyone feels about the situation, I get it completely. This is someone I still love and have a lot of respect for. For many other things, he is the smartest person I know. He has made me feel happy, secure, made me laugh, and feel loved. Of course, he has his moments where he has acted like a total buffoon in an unamusing way. As mentioned before, I will be talking to him about this and a few other subjects we need to resolve if he intends on being with me. (Did not talk today as we were both busy with work today and we live apart.) This is a message to everyone (though I'm not sure if people will see it): I am secure with leaving this man if I find the relationship not in my best interest. Would it suck? Sure, but nothing I cannot handle, have not handled, and will not handle. In the words of a very wise comedian from the stone age: Schwoopsie!


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