does anyone know what acutally happen to first officer murdoch?

No he did not shoot himself as was portrayed in the movie. He was attempting to unhook Collapsables A, and B from the deck to load passengers into them, but this was late in the sinking when water had reached the boat deck. He was washed overboard by a wave, and likely drowned or died of hypothermia in the water. The way he was portrayed in the movie was false, the filmmakers actually had to apologize to his living relatives after the movie came out. Stilla great movie though.

If I remember my reading of different books on the disaster, First Officer Murdoch drowned when the Titanic sank. There's been some speculation that he had even gotten onto a lifeboat but I don't think that is true. He probably died on the boat deck where he was helping people into the life boats.