((((((Brennan))))))
I know what it is like to be scared to tell your parents about your depression. I know now that I have been depressed for most of my life, I am almost 29. I have been dx for 2yrs. I had SI several times in my teen years and never told anyone. 2yrs ago I was taken to the ER for my SI. The hardest thing was to call my mom and tell her that I was being admitted. I got the reaction I was expecting, one of complete shock. Growing up, I was the one to "hold" the family together. For my mom to hear that the family "glue" didn't think life was worth living anymore, was hard for her. However, she has been a big support. We don't talk about what happens at my counseling sessions, or visits with my pdoc; but that is my choice. There have been times that I will talk about my depression, I have to be having a very good day to do that. I don't think my mom understands depression in its entirety.
Your dad is more apt to understand what you are going through. Like what others have said, he may be wrapped up in his own depression to see that you are going through the same things. I think that your biggest fear is the reaction you will get, don't let that fear keep you from getting the help you need. Do you have an adult friend that you could talk to, or be there when you talk to your dad? For me, having someone with me made things a lot less scarey.
If you are afraid that you might take action on your thoughts, please call the SU hotline or 911. You still have so much ahead of you, so much to accomplish. I hope that you will find the strength to carry on and get the help you need.