We are still posting on this "do whatever to have her back" topic. Many are helping you to walk through this stressful in-between emotional time, that is, has it really ended or not?
With all the input on the message you might send, even if she responds positively at some point, there still a high risk the relationship will flame out again. Your message may be a partial solution for now, but there would still be concerns about future months and years.
This is where long term meaningful therapy is so vital. The huge unknown is that no one here knows whether your ex would start therapy much less stick with it and apply it throughout her life.
So be aware that whatever this short term outcome, you will need to shift to
your future and be determined that it become overall positive, wherever you may go and whatever you may accomplish.
