This has happened to me alot. Toxic people ruin your life . You will feel the loss in future. It's better to stay away . And if by chance you got into one. You need to get out of it asap. First start changing your thoughts towards. I'm not telling you to hate. Just to create a scenario and imagine yourself without her. You have to make sure that you are strong enough to tackle her/him tantrums, or whatever toxic trait he or she has. You have to be strong enough to not let him or her affect you in any case. Make up your mind that it's okay . He or she is no one. Don't be rude or anything. But just start emotionally distancing yourself from him or her asap.