Emotional Roller Coaster

Yesterday was Father's Day, and i couldn't help but think of all the good times my father and I used to have together. All the trips to the park, even going to the ice cream store late at night. But as I got older things begin to change. No longer did we go to the ice cream store or on trips to the park, instead I was left at home while he went out. On my 16th birthday I stayed in the house alone while he went out gambling, and when he came back he was drunk and broke, instead of wishing me a happy birthday he told me to get out, and that he couldn't support both me and his habit. And now every year on Father's day and my birthday i go through this emotional roller coaster. And I constantly find me asking myself the same question over and over.

How can I overcome this???