How do I get over the resentment I feel caused by the cheating ?

The only way over feelings is through them. You need to feel the anger and resentment and what they are about for you. Do they make you doubt your own attractiveness? Do you somehow feel it was your fault he cheated?

You need to thoroughly explore the feelings and what is underlying them. Sometimes that is easier to do with a therapist or you can do it on your own. Try writing about your feelings.

Good luck!

You are short-changing negative feelings. It is ok to hate someone that fucked you over. Time is amazing at taking care of things. Thinking you can force emotions is a crock of shit. Accept them and move on.

And with regards to the ex. Write him a long letter about how you feel. And then you don’t sent the letter.

I was cheated on by one of my ex husbands. The resentment has not gone away for me, and never will. It is just not as strong as it was. You will always have that negative memory toward him. I also though hold grudges little longer then normal person though, I think. I find that sort of thing hard to forgive.

I agree with @marinelife. The only way through the feelings is to feel them. This can be painful, so getting some support with it might be a good idea.
When you’ve worked through them, you’ll find that the negative feelings will fade naturally, without force.
I also agree that writing a letter is a good idea. It’s a great release and you can burn it/rip it up afterwards.

The idea of going to therapy to deal with hurt caused by an irresponsible and disrespectful jerk seemed like a further burden on me so I didn’t. What worked best for me was to just let myself hurt and be sad for the time I’d invested, the hopes of a type of relationship that was going to be and then to focus on keeping myself open to recognize the attentions of a better person.

Time. And allowing yourself to feel all the unpleasantness. It’s a process and you have to work through it. Shortcuts short change you and you end up with baggage you don’t know about until it pops up again. Cut yourself some slack. Cry when you need to, rage when you feel it, try to be constructive about it and be honest with yourself and at least one supportive person.
Update the group from time to time and at some point you’ll surprise yourself because you’ll have frgotten how much you hurt. You’ll remember academically, but like a movie you saw a long time ago.