The JCR has an excellent welfare system, one of the best in Oxford.
First point of call is the College Welfare guide, which contains all the info you need about welfare at Merton.
You have at your disposal:
Two JCR welfare reps, Georgie and Nick, who are both peer-support trained, and whose sole job it is to keep you guys healthy, happy and safe.
Further peer-support trained members of the JCR, a list of whom you can find on any noticeboard up around college.
Two Junior Deans for Welfare, Jenny Barrett and Seb Wylie, employed by the college to look after its members. You can contact them via email, phone, or in person. All their details are in the welfare guide, on the posters around college, and on the calling cards you found in your pidge at the beginning of term.
The college Chaplain, Simon, who is another very capable port of call for assistance
The college Nurse, Catherine Haines.
the OUSU support network, which includes the Oxford University Counselling Service (OUCS) and the Nightline telephone service.
All of these people can offer complete confidentiality, and are trained to deal with whatever kinds of problems you happen to have.
More information about all of these are available on the pages under this section.