It's not where he is but WHAT he is…he is a spirit now. He doesn't need his body anymore than you need last year's calendar or the shoes you wore in grade school. Yes, he is FREE from the confines of his body and is experiencing truly unimaginable things. And if he is a spirit, then he is with the other spirits. Go read some Near Death Experiences…it will help. https://www.nderf.org/Archives/NDERF_NDEs.html
After I lost my son I read every NDE on the internet at the time.
Read some of those and get an idea of what your dad might be experiencing.
AND consider this, God commands us to love people BUT people are all going to die. So either God is a cruel God, the biggest sadist in history, or we are going to see our loved ones again. For God would not command us to do something harmful.
Grief is the inability to get to someone you love. If you hurt, it is because you love your dad. And we never stop loving them, so it will always hurt. We just learn to live with it. It is not easy, but one day you will wake up and it won't hurt so bad.
Blessings, anon. Your dad loves you too.