If your husband minimises the affair, you shouldn't join in by calling it a 5 month fling.
Your sexual health was placed at risk and you weren't a thought at the time.
Stop comparing yourself to her... That's an insult to you. She's not worth the muck on your shoes.
Anyone who engages in an affair with a MM, has the morals of an alley cat.
I'll bet she was using him and quite frankly, she would likely have bleed him dry and been after the next mug.
A few questions....
What consequences has he faced?
Has he ever felt you would actually leave?
Have you placed any conditions on reconciliation?
Do any of your family know about the affair.?
And don't feel rushed to file within 6 months. You can file later and you both know the reason.
It sounds like he was infatuated with her and now realises it wouldn't have lasted.
It's all well and good taking her to fancy restaurants, but he would not have been able to keep that up. It's fantasy.
If he's truly remorseful, you need to see it in his actions, I suggest you get him to read the wayward section of www.survivinginfidelity.com
He can post his story and get support from other wayward spouses.
Only by reading and learning will he truly understand how you feel. Let him read the JFO section and see how a betrayed spouse feels on dday.
The gut wrenching, soul destroying feeling and the feeling that you just want the ground to swallow you up.
What does he do now to make you feel safe? Or loved?