Quite honestly, I think the main reason you are upset is all about the effect it has on you - how your friends react, how you get embarrassed, how you think others are feeling, what you think others are thinking, how you think things should be, how you...you...you.
There are other places on earth where none of this is considered out of place - and society hasn't stopped functioning well (because of that). Many also forget that in many tribal cultures of the world, it is NORMAL for women to go topless...so the strictures governing covering your breasts are not 'right' - they are just norms. And following on from that - a man will not lose control of his sexual urges at the mere sight of bare breasts - any that claim such are just fabricating excuses of their own behaviour.
You're also quite young - it's commonly accepted by people with more life experience that women reach their sexual peak in their 40's - so your mothers sexual activeness is quite normal. Do you notice how you don't comment on your fathers sexual activeness (yes, believe it or not, every time your mother has sex, your father is also having sex). Do you not see the discrimination, hypocrisy and disrespect inherent in singling out one gender for disdain - when both genders are involved in the sexual activity?
And touching people is not wrong, contrary to your beliefs. Psychologists who study such think that touch is one of the most healing activities anyone can share with another. In babies, touch is actually essential to their healthy development, and as you get older the form & effect simply adapt but never leave. China has long considered massage one of the great healers of family rifts. Many Friends touch either all the time. Flirting within bounds happens much more than you think - whatever boundaries you wish to put on such...and people also set their own boundaries (which you are apparently unable to recognise). Quite seriously, I consider this aversion of yours one of the most ugly things I've ever heard anyone say - and yet I understand it will have been what you were brought up with to consider 'right'.
And calling your mother a slut? Has she ever slept around? Has she cheated on your father? What you describe of her describes flirtation yes, and also plenty of self control. I think your use of the word again comes back to your own insecurities and fears and embarrassments...oh yes, you, you, you.
You considered suicide because of your mothers behaviour towards other people? That is completely idiotic.
Get some more life experience, start looking at your own hypocrisies and insecurities, and grow up.