I can cope with the breakup better and better, but what if I see her randomly again?

This is fear. It is ok to feel fear, it is intertwined with thoughts they make little fear babies not as cute as real babies
Good thing another fears is they haven't happened yet so we don't need to know what we will do then. Sounds like there is also some shame about anger, the idea "I shouldn't be angry" but it is just like fear: a feeling not a problem. If you believe me at all you're in the green but probably the mind will fight like hell to keep you upset in these ways by arguing, "yeah but"

 

So don't do it, she is no longer part of your life. She is in the past and you don't want her in your present or future so act accordingly to what you want.

If for some reason you see her on the street or wherever just wave at her and keep walking. If she stop to talk to you just say hi, and after a few seconds tell her that you need to go and leave the conversation. If she text you or call you or make any attempt to talk to you, just tell her that you are moving on with your life and its going to be easier to do if you don't talk to her anymore so ask her politely to stop contacting you. Wish her the best and end the conversation.

 

Once you break off/end a relationship, you are under no obligation to ever speak to her again.

don’t say anything—just keep on walking.

 

Analogy - she is dead for you.

Don’t waste your time thinking about her and imagining what will happen if you meet her.

You made your conclusions and get more experienced throught this relationship, now just try to move on and get over her.
She is like she is, no need to be angry with her or try/hope that she changes.
No need to prove her wrong or show off to make her regret.
Just try to find some positive in your experience and thank God that your ways go separately.

If I meet ex I would say hi, if she wanted to meet I would say that I am busy right now and I will call/text her later, but ofc will never call/text.
Just ghosting, no anger, frustrations or regrets