A Poison Tree

I really enjoyed this poem - and connected to it on a personal level (which I think most people can in some way or another.)
The poem begins by sharing two personal stories of "wrath." One was with a friend, the other with a foe. When the speaker was angry with his friend, he communicated his feelings to his friend and his "wrath did end." On the other hand, when he was mad at his foe, he didn't say anything and in his silence, his "wrath did grow." We begin to see what the poison Blake was talking about.
The second stanza Blake discusses fears. Fear and anger go hand in hand, and fear can make people do crazy things they otherwise wouldn't do. He then talks about smiles, implying the idea he is happy about this growing wrath inside of him... He ends the stanza with the word "wiles." I didn't know what it meant, so naturally I looked it up. It means a trick or way to deceive someone. Is the narrator going to play a trick on the foe?
The third stanza the speaker talks about his wrath growing and growing. It had now become that dangerous poison. The speaker then says it "bore an apple bright" - I naturally thought of a tree, because apples grow on trees. The metaphor has been completed. The poison tree was the wrath growing inside the narrator. The foe sees the apple and desires it - obviously because it looks so tasteful. He knows it's the narrator's too..
The fourth stanza the foe steals the apple when he thinks no one is looking, unaware of the poison it contains. The narrator awakes to see the "foe outstretched beneath the tree." He won. The narrator conquered his foe.. But in the end, did he really win?
I think Blake wrote this poem because he has seen what wrath can do to a person - it can drive them mad. My take on this was to be a warning to anyone and everyone to communicate; let others know when you feel angry with them instead of letting your feeling slowly fester until one day they burst. Don't let wrath be the poison tree that cuts you down.