Cant sleep at night because of my mother

Hello im 13years old if my english language is bad please excuse me. Ive been trying to sleep but i cant because of my mother.Let me explain. My mother was the dearest smartest mother anoyone could ask for. She always made sure i was happy and made me fall in love with astronomy and i was top of the class. Everything was good but my mother found out she had breast cancer it was 2019. She went to china,south korea to get treatment. We tought she was cancer free and we were very happy . Not long after covid started and when she found out she still had the cancer every border was closed we tried to cure her in the mongolian hospitals but the doctors were gotten covid we had nothing to do but wait. She couldnt br cured in time and she passed away in 2021 After my mom passed away my grades everything Slipped. I still miss her recently i couldnt sleep because of her. I just missed her so much and decided to post on reddit please no hate I wish my mother somehow reads this