Is it a good idea to attach a cover letter to high school transcripts?

I am about to send out my semester grades to the colleges I have yet to get in to, and the grades aren't reflective of me. In the first 4 months of my senior year, my best friend died in a car accident, my boyfriend of 2 years found out he was schizophrenic and basically lost it, and my grandpa had a stroke and we have been moving him into assisted living. Needless to say, it has been a rough first semester and my grades are reflecting that. I know that these grades are a critical part of the admissions process, so I have been thinking about attaching a cover letter to explain these obstacles. It wouldn't be a sob story or a long essay about excuses, but I think the colleges should know and maybe be able to understand where I am coming from. Thoughts?