他肯定不会原谅你 should be accepted
一定、肯定、铁定、注定、必定 should all be accepted.
注定 is more like destined , 必定 emphasizes on the inevitability due to causality or the nature of the thing, so I don't think it fits either. 铁定 should be accepted, but it is very colloquial.
all dramas in a nutshell.
What did I do to not be forgiven? Duo please.