A wet sleeping child is less trouble than a dry fussing child. If you get very worked up, your child will see this. He will see that by wetting his pants, or by not having a b.m. In other words, he will be in control of your behavior. This is quite an accomplishment for a two or three year old and is the last thing you want.
All children have accidents during the normal course of toilet training.
But if the training is going badly, drop the whole thing for the time being. Leave the potty chair in the bathroom. But put your child back in diapers. Don't bring up the subject of toilet training at all for a while. Try again in a few weeks.