I really think you hit on the issue here,
but how can I do that when I am not truly happy with myself.
It is important to share with your wife how you are feeling at the moment you are feeling it
. If you were to really seek her help, to share that you feel like you are being pressured from inside, that sex is surrounded by shame and control, you and she may be able to find a safe place inside you where you can put the good feelings about sex and intimacy with your wife without the negative ones.
Make sure to share with your wife, affirm and empower her. She is a wonderful supporter from your description, but she is frustrated. It may be because she does not understand this issue, it may be time to completely open up to her about it.
Important too is to make sure that any coping mechanisms concerning sex, viewing porn, fantasizing or any other extreme sexual activity is stopped for at least a time to see if that may be affecting your thoughts and feelings about sex.
Come back and tell us what happened if you are comfortable, ok?