It has sadly become consensus to try and distance oneself by being part of the pitchfork mob. And I haven't found an age mentioned in the article - e.g. the age of consent in Germany is 16 IIRC, in which case the legal problem is when the older person has a position of authority / responsibility, not the actual age. And - age of consent or not - a relationship with a big age difference among adults is also creepy.
Anyways, I remember my thoughts as a teenage boy and I would definitely - even in hindsight decades later now - have fantasized about this ^^ Even though I would have probably chickened out g
Your mom is unfortunately mentally ill. Whether from upbringing or from organic damage to the brain... who knows. There's really not much you can do about it - parents especially are highly unlikely to listen to advice or anything from their children. Try to remove yourself from your mother as far as possible. Minimal communication, minimal contact.