It sounds as though you are struggling with some very big, scary thoughts and emotions right now. With regards to talking about the things that you think make you poisonous or a bad a person, perhaps discussing it somewhere anonymously such as on here, or with the
Samaritans might constructive as you could kind of test the waters so to speak, with people who don't know you and whose opinion might cause a less emotional response within you than that of those around you who you care about. Another thing to hold onto is that the people who believe they are bad or 'poisonous' very rarely are, in fact often I have found in life that the people most inclined to beat themselves up and who think badly of themselves are the people who in fact least deserve to.