Please help me,im really sad and i dont know what to do with this situation?

everything started when one day i took my mothers blackberry searching for some pictures of my little sister,but instead of that i found like 6 pictures of my mothers boobs..yes, my mothers boobs, i thought she took does photos just for fun or something so i didnt pay attention to it, the next day i was looking at the people that she had on bbm and i made a mistake and instread of clicking on the picture of a man that she had in bbm i clicked on ^view recent messages^ and then it i saw this conversation with a man that said....^man^:dont worry baby i didnt save the pictures,i only saw does delicious boobs but i didnt save them...and them my mother just answer him with some faces....omg im so sad and so dissapointed,i hate being in this situationn i dont know if i need to talk to her or something,i hate that she is cheating on my dad and i hate that she is not thinking abaout what would happen to our family if she keeps doing that,can someone help me? I REALLY DONT KNOW WHAT TO DO!! ihate it SOOO much,i cant beliave she send does nasty pictures to that f*cking man im so sad