The lost time that you could have probably found another woman, the despair that for a third time the relationship didn't stabilize to the end, not having enough mental strength to stop contacting her because of how much emotionally bonded you were (and are) to her will make you have a not-so-good personal view of her. Not forgetting the hurt from the breakups and the lost time trying to work out on a relationship that has sadly come to an end, once again.
You can change your personal view about her by first of all analyzing yours, especially the negative side. Some things about you might have resulted in the frequent breakups or affected the relationship one way or another.
Another thing is to remember that humans are different, and you can't change them. You might have struggled to change her attitudes or behaviors without any success. Unless a person desires or asks for help to change certain behaviors, it will be fruitless to force them or work on changing them. The best is to let them know about it and how they can change their untoward behavior. Also, you can ask them if they want to work on their negative behavior, they can ask for assistance.
Remember the good side of the relationship. Even the evilest people have a positive side about them. There are things about her that made you like and love about her. People who have undergone several breakups with different people will say there are good aspects they found in their different partners.
Choose to forgive her. This will loosen all the negative thoughts you have about her including hatred and bitterness. This will assist you to appreciate human weakness and that man always err even when they don't want to admit is the case.
Try not to contact her for two weeks if a month is difficult to exercise the rule. You should inform her that you don't want to contact her to reflect on several things, and stabilize your mental state including allowing the healing process to commence so that you don't fall into pieces; never to recover from the breakup.
It is evident your relationship with your ex will never work out although in some circumstances it's possible. The uncertainty is whether it will work on yours or not. You might try and it works out or not.
It's time to work on yourself. If you succeed to exercise the rule in two weeks, you should continue it for a month until you've healed from the breakup. When you've healed you'll have a clear perspective of the relationship - give it up or try once time.
It's not advisable to get back with your ex. The best you can is to thank her after completing no contact for a period of one month or more. And also, provide her an insight about her and which places she needs to improve so that she doesn't end in another breakup when she engages in another relationship.