I want to leave my fiancé and my healthy relationship. I am 28F and he is 28M. Can someone give me advice on what I should do?

I have been with my fiancé (28M) for 4 and a half years. He is perfect in nearly every way. Our wedding is supposed to be October 2025. Within the first year and a half, I lost my grandma and my dad. He was very caring and supportive through it all. We have never had major issues, no cheating or anything other than the average argument here and there. I recently lost my little brother and at this point I feel the urge to leave this relationship and be on my own. I am lost on what to do but I feel like I can’t get married at this point in my life. My mom passed when I was 6 so losing my grandma, dad, and little brother all in the last few years has taken a toll on me. I don’t know what to do.