it is very hard to maintain that balance – i agree that you have to act normal and nice (this is going to be a continuous problem in getting a job, at work place) – if act rude, will be very difficult for you in jobs. Fortunately, in nursing, i would imagine that it’s mostly women, so stick around the women, especially those who also like to stick around the women. do NOT be overly friendly to the men at all – be nice, formal, and professional.
after a while, they’ll see that you’re different and will respect the difference.
do NOT hang out with them at other times – do go to the library, places that are separate, during free times.
it’s a tricky balance, but must maintain that balance if working in secular environment.
it can be done – just must always be careful – and not act as free and extroverted as normally would do among your frum friends.