I think it's very scary to talk with people when I feel they are wrong. At most I bite my tongue and let resentment fester inside me about it.

Don't let it stop you from going back! Having an honest discussion about things you felt were wrong is something to be proud of, not ashamed of. You didn't attack her or call her names, and you should not be feeling hatred at yourself.

You sound a lot like me, afraid to voice an opinion that differs from another's and scared to return to the scene of the crime, so to speak. These are strong reasons for you to go back! You found your voice now don't silence it so soon.