The other day I came home to find my parents talking in their room. They only do this to talk about private things, stuff they don't want to tell me. It so happens that I left a tab open on the internet to a page about a book on homosexuality. I immediately start freaking out, and close it. I can't believe I left that open when I left the house...I never do that, and I'm really careful about those things. I calmed down and later found out that what they were talking about had nothing to do with that. I really hope they didn't see that, and they aren't giving any hints that they did. It just upsets me because I don't know what I'm going to tell them if they do come across something like that. Do I lie or tell the truth? It makes me anxious.
If you are ready to come out to them, tell them the truth. Just be honest with them. They will love you no matter what.
Reading a book about homosexuality is hardly a sure sign of being gay, homosexuality is fairly big in the news at the moment so if they did see it, they probably just thought you were curious about the subject. I wouldn't worry too much about it if I were you, it's not like you were looking at something a straight person wouldn't look at. If they ask you why you were looking at it, just say you were curious about it and wanted to find out more, if you aren't comfortable lying to them then you could always bend the truth. It's not ideal but if you aren't ready to come out then you aren't ready.
Just an option. When I came out to my Dad, it was because he asked me about some recent behaviour. I always find it easier to come out when people ask, rather than having to bring it up or trying to move the conversation in that direction. So if you're ready or can muster the courage, and IF they do ask, just think about seeing it as an opportunity rather than a problem. Peace!