Family worries?

i done something stupid few years ago i spent �30000 that i received from an accident,my parents think i still have it in bank,now im married with 2 fab kids & building a house at home with there help.i know im going to have to tell them,there will be a huge row if i tell them face to face when we go to see them later this year should i write a letter & hope for the best or tell them on phone & what do i say