That your life is happiness or suffering depends a lot on how you feel, your outlook. You look at the good side of life, you see it beautiful. On the contrary, you look at the bad side of it, you will see it is gloomy.
You can only live once. Yesterday has already gone. Today and tomorrow are all you have. You will not be able to see the beautiful things ahead if you keep looking at the bad things.
Because when you are absorbed in looking at the unhappy things like the pain in the past, your heart cannot open to see the good things that await you. You are losing the happiness that you deserve to have.
So forget the traumatic past. Sometimes, you just need to smile a little, light a match and burn the bridge of the past. And let them disappear from your life.
Enjoy, love your life now, and put your hope in the future. Live and learn to improve, and never look back.