Keep them as only thoughts, dont follow through with the thoughts. I know how you feel, as I wanted to do the same. Look God wants you alive because he has a plan for you, and if you take your own life to try be with your Dad. I miss my father, and mother that I never seen, She passed away when I was 1yrs old, my father died when I was 12yrs old, so you see, it happens to the best of us. But You must carry on living your life. Because God has a wonderful plan and path for you. and for you to carried them out you must live for God. as God lives in you.