I understand how difficult this can be, Sahil. You're not alone. I can also tell you that the more you keep saying you "can't" forget and you "can't" let go etc., the more it will happen. If you can start to change your language and say things like "I haven't been able to let go yet," this opens the door a crack. It allows movement. It allows an energetic shift and someday you'll notice that it feels lighter. As long as you keep insisting that you can't, you won't. There's nowhere to go with words like that.
You could also try "I'm willing to forgive" or "I'm open to learning how to let go" - anything that allows movement in the direction you want to go.
We don't forgive for those we feel have hurt us; they don't care at all. We forgive for ourselves - and forgiveness just means "I don't want to hurt about this anymore."
I wish you all the healing you need.