What can I confront my mom about lying?

[Solomon Terra]

I think the best approach is honesty. You might want to preface it with an apology, something like, "Mom, I was being nosey and noticed some messages on your phone from this guy. I'm sorry for snooping and I know I had no right to, but I did and now I know about him. Are you cheating on dad?"

That takes a bit of courage, but certainly cuts through any b.s. she might want to fling up to protect herself with.

As for your emotions, try to think objectively. While it sounds likely that something untoward is going on, it might be something innocent, too. My own mother sometimes talked to some of her past boyfriends - as friends, purely innocent - but still didn't want my dad to know because it might have upset him. Acting sneaky raises suspicions even more, but it doesn't necessarily mean that something terrible is going on. So just try to face it with the notion that until you know for sure there's something to be upset about, maybe there isn't and so you should just try to dismiss those feelings - for the moment, at least.

The longer you hold off, the longer it will eat you up and make you miserable. So I'd recommend doing this as soon as you can.