My father who just passed had a mental illness?

I'm very sorry. You should be more happy than sad since he'd been through much in his life with all the bipolar illness. And death is salvation.. Your dad is resting in peace now, isn't this much better than him living with bipolar and staying away from his kids and missing them and collecting toys for them? Just look up in the sky and smile to him and tell him it doesn't matter if he'd dead, he'd always be in your heart because that's where you kept him all your life. Love you.