put yourself in your dads shoes and think how he is feeling , its probably best to sit down and explain to him how you feel and what your resons are then take it from there , my dad walked out on us when i was 6 but i still wonder what he is doing and if he is ok after 20 years of no contact , i still dont know his reasons for leaving and my mum wont talk about it , you will only regret not asking why in years to come