express regrets on my week performance in university then show my reasoning(adding to my grandmother death can you please add more convincing reasons) then future plans to help me be more successful in my university career.

I have been suspended from university and they requested a letter to explain why my performance was week. Can you please mention the fact that my grandmother passed away in the middle of the semester and it had a major effect on my performance, basically, include the following in the letter: express regrets then show my reasoning(adding to my grandmother death can you please add more convincing reasons) then future plans to help me be more successful in my university career.