Six months ago I started dating my girl friend's male roommate. At the time, my friend warned me that although her roommate was a good friend, he was a notoriously bad boyfriend. I explained to her that I just wanted to have fun, but she still acted weird about it. Five months in, I learned he was hanging out with a lot of other girls, so we decided to end things. I was disappointed it didn't work out, but I knew it wasn't meant to be.
A few weeks ago I found out that I have genital herpes. I knew immediately it was from him — I've only been with one other guy who was also a virgin. I had asked him before we slept together if he had been tested, and he said he was totally clean. Obviously I was very upset by the news and confronted him. Naturally, he claimed that I must have picked it up from some other guy.
When I came crying to my friend, she was extremely distressed by what he had said. Apparently, he had confided in her a long time ago that he had herpes, but asked her to keep it a secret. When I heard this I was furious. I know that they're good friends, but I couldn't believe she'd kept that from me when she knew I was sleeping with him! I feel beyond betrayed, but she says she "tried" to warn me. Is her omission of the truth forgivable?