As a person who has unknowingly married into a family of ADHDers. i think he didn't really mean it but very likely he could be neurodivergent.
For your reference, I have heard my husband told me he wished I was dead countless times. Is he a good person in general, yes; but his anger issues can really grind me off. And I am in constant battle to remind him to be respectful.
Back to your fiancé, he will cry and beg you not to leave him if you call off the wedding, Or he will threaten you. Either way, you have to make a choice whether you would like to live with a man like him, the same argument will appear again and again, he would also start saying more hurtful things as the intense love fades away due to having children and living together for long. It's how his brain works and he will not change a lot, ask yourself if you can bear with it.
Having said that, no one is perfect. If that's okay with you. Then, it's fine.
if you decide to call off the marriage, you have to be vigilant as people with anger issues can do extreme things. Avoid being with him alone and change your door lock, and let every family member be wary of him even though he behaves in amicable manner.
Sorry you have to go through this, giving you lots of hugs.