Determine the valence intensity of the following tweet, considering the mental state of the author. Assign a real number between 0 and 1, where 0 denotes extremely negative and 1 denotes extremely positive.
Tweet: Blah blah blah Kyrie, IT, etc. @CJC9BOSS leaving Boston is the real news and I am #devastated! #celtics #fave  #someonegetmeajerseyteeasap