Nothing, forgiveness just means you’ve let go of negative feelings.
You can forgive and still cut the toxic person out of your life. I don’t hate alligators, in a way I love them but I don’t hang out with alligators because I know gators gonna gate and I’m prone to lose an arm the more time I spend with gators.
It’s the same with forgiving humans, lots of people suck and you can make yourself miserable being mad they suck or you can cut the sucky people out of your life, accept they are who they are, and go find some decent people to befriend.