What is sex? Is the most the intimate between a couple/the most close a couple can be? What is most important in a relationship?

I'm 19 from Malaysia.

I grew up in family which is very religious. They believe that one's body & also sex is a  holly & precious gift given by god. Thus,its a must to take care of it well. My parents and relatives are very strict upon dressing and don't allow their children wear tight, low cut and short dresses. They also warn them to constantly adjust dress. They think sex is the most important & intimate in  relationship.

As society, one's sexual behavior defines his/her dignity (mostly applied to women) For example, when one(mostly woman)wear provocatively, the people judge based on it. They consider her a slut/prostitute who doesn't know how to control urges. Moreover,people who have multiple sexual partners/date a lot are seen lower in level. They define sex as something that should only be done with the monogamous. To make it simple,sexual behavior define one. When I compare with Western,its totally different. People there consider sex something fun & have multiple sexual partners before marriage. Much worst,they engage in casual relationships, nudity, pornography and more. Here one does like this loses self respect. People there are very open about their sexual life. They take nude selfies, sex tape and more. Whenever I think about this, I get disturbed a lot (headache,mood out&etc) Since I'm adhering too much to my culture, its very hard for me not even follow but accept it.

I need help to get out of this and change my thinking.It would be more helpful if someone can spend their time to discuss about it. *one have sex past is considered second hand too (forgot to state it)