I was just wondering how bad is hereditary hemorrhagic telangiectasia?

Not that bad: You will see in the medical literature that most people with hht have a normal lifespan.The commonly seen skin lesions and nosebleeds usually develop during childhood. The avms (arterial-venous malformations) are thought to be present from birth, but don't have to cause any symptoms. Frequent nosebleeds are usually the most common symptom.