One of the hardest parts of dealing with and recovering from affairs are due to the gaslighting. Please google gaslighting and affair or gaslighting and addiction. It might give you better insight regarding your panic attacks and anxiety. (We have them because we know something is off with our partners and how we are being treated and then these reactions get used against us to continue the gaslighting cycle)
Staying with him right now is dangerous for your soul. For marriage and reconciliation to work both people have to be in it 100%.
I agree with blu wave. It is impossible for you to get your ex to see anything. You are looking at things from a perspective of someone trying to save their marriage and think he is too. He is not.
His perspective is as Vanilla says someone feeling entitled right now. He is destroying you to justify this entitlement. And if you stay with him he will continie to villify you to further justify nehaviors that are not normal in a healthy partnership. HIS BEHAVIORS ARE NOT NORMAL IN A HEALTHY PARTNERSHIP. Any validation will only give him further proof you are wrong and weak and he is in the right and desirable. You are right to get away from him and take care of yourself. You cant get him to see your perspective. Dont try. It will firther your anxiety.
I also do not believe in MLC. I think often times we just dont know who a person is at their core until they are pit to the test. These things (affairs, walking out) usually come at or after life stress. Job loss, death, health issues, children. These people are fair weather friends at the core. And it just takes bad weather to see it. They were never truly committed to marriage.
When they leave and come back, all it usually takes is another life stress for them to leave again. So evaluate why you fighting for this to work.