What do you do when you are the toxic person in a relationship?

Assess and deeply think of all the things you could be saying or doing that is toxic in the relationship. Take note of what your partner has complained about you, and ACKNOWLEDGE it and make efforts to try to stop doing/saying those things. Do not dismiss what her concerns are and deny them. DON'T DENY what you do wrong. By denying, you are not caring about how he/she feels and come off as thinking you are perfect and can do no wrong. I know about this, my ex was toxic in subtle ways and I didn't realize it until it ended. He denied, denied, denied when I brought up what he was doing. The least he could do is say, "I don't think I do what you are saying, but I acknowledge how you feel and will be more aware of my behavior."  It's good you are asking this and admitting you can be toxic, that's the first step in improving yourself.

Go get a peace of mind