The Spiteful Letter by Lord Alfred Tennyson?

I have to yze this poem as an english ignment, its due this monday. My problem's not the ysis, its understanding the poem. It's confusing me so much. Who is it dedicated too? I thought it might be an elegy to his friend Hallam, but then i noticed some sort of competition between the speaker and someone. Please, somebody, i need some help. URGENTLY!