My parents keep having sex? HELP!!!!!!?

Well I am 14 years old i saw my parents have sex when i was 8 years old and i was traumatized and i am scared for life i can't stand it most people will say it is natural but when it is your parents you feel completely different my dad works nights from 8:40 to 6:40 so he almost never is at home at night but every two weeks on wednesday and thursday he is at home and is almost always bugging my mum i can hear them in the bedroom most of the time my dad goes to work at 10:30 which and at 9:30 me and my sister are in our bedrooms when my dad is here he almost always tries to get my mum to have sex and i can hear them i not sure if it is genital contact or just kissing but i hear them kissing i just heard my mum say" your going to work in a few minutes stop turning me on" and a few months ago he said he wants to do it at least once a month i can stop it by letting them know i am awake and my dad will stop i have got head phones but every night i go to bed thinking about this and i can not help it because it is so traumatizing for me now and when i was young i can't get over it can some one help me find way to get over it or make me forget it i really wish i could forget it.