Any ideas, please?

Alright. I know I need help with my depression. I suffered from a stage of depression five years ago that was very severe, but I overcomed it for a good three or so years. Lately, though, my depression has re-surfaced badly. My mother died in December 2008 and after that I was depressed until I met my ex-boyfriend who made me happy for a while. After my ex-boyfriend broke up with me in July, I tend to get sad even at the moments I would think I'd be the happiest during. I especially sadden seeing him or thinking about him, but this is hard not to do since we have to see each other all the time at school and at our many theatre rehearsals. No one knows about my depression other than him, too. I tend to not like talking with friends about my personal life or feelings since most don't understand them. In fact, I smile every day and tend to smile even more on the days I feel my most depressed because I do not want people asking me what's wrong. I want to get professional help, but since my depression is not apparent I am looking for suggestions on how to approach my father about getting therapy or mental hospitalization. I would also appreciate any self-help techniques or ideas for the time being because although I can control my depression, I want to fight it and conquer it to the point that I can become a better person.