Is it better to stay friends with your ex or have no contact with them?
I think that it is important to question if you will be okay with only a friendship from her. What do you have to gain out of the relationship? Sometimes being friends with an ex can be very complicated as there may be a lot of unresolved feelings there. You stated that you have worked really hard for her to see the changes that you have made. Ultimately, were those changes made to try to resolve and restart the relationship? If you still have feelings for this person, I think having a friendship can be very difficult as you may find yourself wanting more than what they are willing to give. Would you be okay just being friends?
It is possible to be friends with someone that you were once romantically involved in, but can be hard. I would just really question what you are hoping to gain out of the relationship and if it will be satisfying to you to only remain friends.
Are you happy about her current relationship? That is something else that can be very important to ask. You don't want to cause issues in her current relationship. I would also question why does she want to be friends with you? Are there any expectations for this friendship? It really depends on your comfort level in regards to how the relationship ended.
I think you should also consider how the relationship ended. Did it end on good terms? Were there things done that are hurtful that you may not be able to get over? Do you even want to be her friend? I think just a lot of self reflection would be very important to understand what you truly want and what you need out of a friendship or relationship.
Sometimes the severity of the relationship can also determine if a friendship can be hard. I think that it is very possible to be friends with an ex if you are willing to put in the work and so are they. It's just important to really question the point of the friendship. I hope this is helpful.