New semister is going to beggin. We have to choose the obligatory lessons we want to study this semister. If I don't choose an obligatory lesson this semister, I will have to study it an other time. I can't get rid of it.
 But we have to study "Family Planing" which speaks about relationship in marriage. (male and female students will be taught seperately)
  Is it sinful if I attend this class? I have no other choices.
I am of a very delicate nature, any mention of private matters can make tigger me. What can/must I do?

I say first get baptized into the Catholic Church before taking the course. If you are easily aroused by mention of private matters (as I think that is what you meant by saying you have a delicate nature), then it is better to have the Sacraments of the Church, especially reception of the Holy Eucharist, to help you overcome the temptations.