Yes, that gum is toxic.
If you find the "healthy" kinds, make sure to read the ingredients, sometimes the xylitol gums also have aspartame. Have you done total body cleansing? It would be better if you got rid of the root of the bad breath problem. Then all you would need would be to chew on some parsley or a mint leaf, or maybe eat an organic breath mint made with molasses or something like that. Or just brush your teeth and tongue.