I am a 24 year old female I have been seeing a 42 year old married man for 6 months now?

When I first started seeing this man, I didnt want anything to do with hm or his personal life.. I just wanted to have some fun.. But as the months past I started falling for him more and more everyday.. I no he likes me as well.. Ive met all his friends, we go out in public together, we do everything together. Its just killing me that he will never be mine.. So can someone please help me.. I dont want to fall deeper for this guy and get really hurt at the end.. I want to let go, but I just cant...