Help me ASAP very inportant!?

my mam and dad said they were going to a party tonight and wouldnt be back until about midnight so once they had left i invited my boyfriend over and well you can pprobably guess what happened but since noone was home i was moaning quite alot then all of a sudden i heard the tv downstairs turn on then i heard my parents talking so we quickly got dressed i quickly turned on some music so it could have just been the music but im scared in case they hurd me what do people think i should do because im scared to go down in casee? thankyou soo much anyone who can help