The only significant aspect to your natal Mercury is a 'dual square' with Uranus conjunct Neptune with an 'assist' from Pluto. This , in my opinion , reveals the source of the problem .
The 'problem' is an 'oppressive pattern' (See also , 9 and 10 of swords in the Tarot) resident in consciousness and emanating from the Mercury-Uranus/Neptune square.
Handling this should be your primary activity, the most important item in your life.
The 'Catch-22' is that the 'right use' of Mercury (mental focus) is required to handle this matter and Mercury is 'afflicted' !(?).
The 'meditation' approach that you mentioned is key ! BUT your 'meditations' are best to NOT be in 'reaction' to the oppression but, rather, to be pro-active and focus upon the way that you desire your consciousness (Mercury) to operate .
Your natal Mars is also assisting the problem , why ? because Mars is the 'servant' of Venus (heart) and Mercury (mind) ....... so changing-your-mental-patterns is the only long-term solution.
Taming the mind is the absolute essence of metaphysics , including astrology , so your situation is not exclusively unique in-so-far as what must be accomplished is concerned.
So ? what to do . . . . .
My suggestion is that you MUST 'get outside of yourself' ....
contemplation of spiritual deities (Christ , Krishna , Buddha , Venus , Goddesses , etc) because there is a vortex of energy available for you to access that has built-up over thousands of years . Be constant until you find a 'deity' that overpowers the oppressive pattern, and then stay with it !
If you can get-in to yourself deep enough then give yourself the feeling of already having conquered the guilt, etc. , even if you have to become another person (invent one) .
Also , 'directing' your thoughts to 'go through' your heart (Venus) rather then just emanating from your head will also be helpful ! Shift your psychological 'originating-point' from 'mind' to heart .
With persistence , you will succeed and the oppressive patterns will diminish and fade into non-existence.
The 'why' is unimportant (why the pattern?) . . . it is the result of a 'square' so it (the 'why') is recessed in consciousness . . . .
Movement , as in dance , or some other activity wherein you can 'let-go' of thinking will also assist you . . . . sometimes , even a juice-fast for 3 days will clear-up adverse mental chatter . . . . it frees up energy !
Your 'mind' is showing you a 'bad movie' . . . . walk out !
Mind: terrorist or friend ?
http://www.youtube.com/watch?v=O0QoaqX5xVA
I wish you great success !
Ion