我真的非常后悔 I really regret it

我非常后悔 I very much regret

他非常后悔 He regretted extremely ; He'll regret it ; He is very sorry

我真是非常的悔恨 That I regret so desperately

我感到非常后悔 I feel very sorry

悔改前非 repent of former misdeeds

我现在非常后悔 I am very sorry