I know what resentment means. My ex shows it all the time. My questions are after 5 months apart why still does she fill that way? And how can I correct that? Meaning is it because she is not over the situation or she needs closure with me, or she is mad at me?
Help me out here please.

Simply she is holding it against you and she possibly likes it that way.
Let her go it is not your problem how she chooses to feel. If she wanted closure she would be letting you know because people that want closure make it quite clear.

Bruv a woman can resent you for the rest of their life! 5 months is nothing. You cannot correct it because you're no longer apart of her life and she isn't in yours. Only she knows why she's behaving in such a manner and frankly it should be the least of your worries.

Who cares if she resents you? She will get over it eventually... Let her lie in her own bed

After 5 months, why do you care what goes on in her little head?? Why make this a bigger deal than what it is.

Letting her hate you is a gift. Let her. Attempts on your part to "calm her" or "ease her anger" will actually frustrate her all the more.

Don't worry about her. Let her deal with your relationship ending the way she wants.