HIS DARK PAST. HOW SHOULD I REACT?

Weve been together for more than a year now.

As a girlfriend i cant avoid asking him about his past. His exes, how many have he slept with and things like that. At first he told me stuff and said that thats all and nothing more but days after our anniversary he said that he has secrets and so somehow i forced him to tell me.

HIS DEEPEST SECRET... He had immature and casual sex with two of his cousins several times in highschool, who live right next to there house until, of course, today. But he said it was all in the past. Past that doesnt do anything between us today.

I know he loves me but i just cant avoid feeling something hurting. Thinking he wanted it, they did it. Several times. With cousins. Who live next door. Until today.

Im in my review for board exam for a konth now and i still have months to go over til i can go home. I cant consentrate to my studies.

Pls help me. Im trying to cheer him up and cheer myself up in secret but theres still heart ache in me. HOW SHOULD I REACT TO THIS! IS MY FEELINGS TOWARDS THAT PAST NORMAL??

THANK YOU SISTERS!! GOD BLESS!