I need help. I'm so confused. Am I cheated on?

Hello, needless to say I never thought I would be searching infedility support groups on this sunny beautiful Saturday. Yet here I am. I am 57 years old and my pilot husband is 50. We are married for 30 years. With all ups and downs I thought we have a wonderful and solid marriage based on honesty, trust and respect. It is hard to summarize everything in the short message but the bottom line is that he never wanted to divorce me. On 2 occasions in the last 7 years I happened to find 2 messages for him from other women that seemed to be a bit too " friendly" but after thinking about it, I discarded my thoughts as just unjustified. After all my husband is always coming home, always accounted for, constantly working on improving our house, our accounts are joint, no trace of missing money, no change in behavior. Yet those 2 past incidents were occasionally getting back to me. 6 months ago I asked him for his email and FB addresses and he gave it to me. Only 3 weeks ago I decided to check his emails, not sure why. Inbox was clear, deleted emails nothing but then I hit sent. And this is why I discovered 2,5 years of history of multiple images of different women, dressed and nude sent to his Gmail account (unknown to me). One woman in particular showed in 50 emails. My husband' comments on her pictures were devastating: ONLY you, perfect body, I want only you and more that I can't say here. The emails indicated that they talked on the phone and planned to meet in Washington DC, where she lives and my husband flies often. They never met because she found out that he is not based in Washington and she wanted someone close.... The other time a woman ended my husband attempt to seduce her because she didn't want to do it with married man. What if any of those women wanted the serious relationship? I am so lost and confused. What do I do?