How long have you been practicing the suggested techniques? Perhaps there are feelings of deep anger you've suppressed for a while that rose up when you started facing them. I think the point is to let the repressed emotions rise up to the surface so that they can finally be let go of. I've had a lot of anger issues myself, so I can definitely relate to what you describe.

I also had a similar experience with positive affirmations. When I first started positive self-esteem affirmations, I ended up feeling worse than I did before, with more intense self-loathing. I figured this was just my pent up emotions being let out, so instead of giving up I kept with it. Eventually the self-loathing thoughts subsided and I started to make real progress towards higher self-esteem.

Thoughts and feelings are only powerful when you give them power. When you feel how intense it is, yet see it for what it really is, just a passing feeling that has no real power, you can let it go any time you wish and move into a clearer state of mind. It takes time, of course. Progress can't be forced, or it just increases resistance.