My boyfriend broke up with me because of my past. Is it my fault or his excuse?

Im 26 so is he.
we've been so in love. so much memories. And I must say he truly loved me and I was happy.
I've been single for 4 years before meeting him. Then we met, I was scared to love again but he encouraged me to trust him.
After one year he broke up with me because of my past. which is:
before meeting him in one month, I've done an affair with a married man. sure it was a mistake. but it was my only mistake in 4 years. even the only relationship i did. we all do mistakes. regret. learn. i stopped the affair when i find myself ready to love. and told my boyfriend backthen about it and about my first love 4 years ago i told him we didn't slept together with the married man and i enjoyed teasing him back then. there is a lot of psychological reasons.
After a year, he changed, cold heart, careless and told he was keeping in his memorycard screenshots of hotel reservations and nude pics concerning the married man and that I lied to him backthen. Then he started to accuse me of being a slut and sleeping around before knowing him.
It was a shock.
1- the chat with hotel pages are true back then i was planning to go with him but backed up. it didn't happened. that's why I didn't lie to him. I cried and begged him to believe 0.
2- I though he knew that there must be pictures involved I felt embarrassed and didn't want to hurt him by telling details.
3- I discovered even worst nude affairs and chats in his phone that he didn't told me about and I forgave him.
4- my boyfriend told me so everyone else after break up that I've been loyal and never had doubts in me during our relationships but after seeing my "past" he doesn't trust me anymore and feel disgusted.
Why he chose to talk about screenshots he's been keeping for one year? even if he found out recently he knew what kind of girls I am I don't deserve this. I feel so much pain to lose the one that loved me because a past mistake..
My boyfriend broke up with me because of my past. Is it my fault or his excuse?
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