How Can I Fix This When It Seems So Hopeless?

My fiancé left me around the holidays and I'm still struggling to cope or make sense of it these last few months.
He was truly my best friend. When we met, I had cancer and he always made my favorite food so that I would eat even when I didn't want to. He held me as I watched my father pass away from cancer. We had dreams of having our own business together once he finished school and planned to get married later this year.
Things got especially bad after my dad died. I lost my job due to health issues and I struggled to find something else. This made me incredibly depressed to the point I was suicidal. I was exhausted and miserable and in pain from trying to take care of it all on my own and broke down practically begging for his help, which he couldn't seem to muster. I understand everyone has their limits and I wasn't pleasant. Events in my life put us through a lot, but I never saw it breaking us. I always thought I could count on him being there.
Life is so empty without him. And I'm having a hard time figuring out if who I'm still madly in love with even exists. Shortly after I was taken the my mom's house on suicide watch and started therapy and meds, I reached out with a sincere apology and thanked him for loving me. He never responded. A few weeks later even though I only reached out once, he blocked me. He has changed into this cruel stranger and it hurts me deeply. I very much miss my best friend and I don't know if there is anything I can do to fix this.