There's some research data to suggest that nolvadex COULD make it worse.
Letrozole will absolutely NOT make it worse. In fact, it's about the only sure-fire way to combat progestin gyno.
Letrozole can drop your estrogen level to practically zero. Without estrogen, progesterone or prolactin cannot cause gyno. However, dropping your estrogen so long guarantees that will have no libido. It also really messes up your lipid profiles.