Tenants in a Long Island apartment building say they have been living in conditions so horrible that some can’t even breathe in their own homes — choking on mold, dodging mutant “X-Men” bugs and enduring relentless water leaks. Tina Shuford, president of the tenants’ union at 100 Terrace Ave. in Hempstead , said she hasn’t used her own kitchen in years and is forced to wear a mask and gloves in her apartment on doctor’s orders because of the mold, with her belongings stashed in storage bins to protect from “constant” leaks. “Welcome to Hell,” said Shuford, who sued the building’s alleged “slum lord” then-owner, to The Post. Tenant union President Tina Shuford says life at 100 Terrace Ave. in Hempstead, LI, is “hell.” Gregory P. Mango for NY Post Shuford’s lawsuit — which has now switched to targeting the building’s new owner — claims the conditions are illegal under New York state law.…