If you believe you can ask someone for forgiveness by speaking to them in your thoughts then go for it. Ask for forgiveness and wish them well and according to your belief you will be at peace.

I have a ritual of forgiveness that I have practised:

I ask everyone I've hurt in thought, word or deed to forgive me.
I forgive everyone who has hurt me in thought, word or deed.
I forgive myself for hurting anyone in thought, word or deed.

Peace and love,
Enocia
related link: Gifts of Love Come in Many Forms