I have been in your shoes. Here are a few things I thought before telling my wife:
That was less than 6 months ago and THEY WERE ALL LIES! Since then, I've told my wife, family, friends and started a very public blog about my experience (HelpImGay.com). Today... I've never been happier.
After coming out, these are the truths I've discovered:
Telling your wife you are LGBT doesn't change who you are. You are still the same person 5 minutes AFTER telling her that you were 5 minutes BEFORE you told her. It could take her some time to realize that, but its true.
I KNOW THIS IS EASIER SAID THAN DONE! I will be the first to tell you that disclosing to your wife you are attracted to men (have had sex with men, are addicted to porn, or have a boyfriend) is not easy to do. BUT, after doing it you will be able to confront the issues that bringing you shame and making you feel like crap.
I would make the disclosure during a therapy session so the therapist can offer support to your wife. She might have a whirlwind of emotions or... she might say, "I've known for years." Either way, professional help could be welcome.
Now, the answer your question... "Is coming out the answer?" Only YOU know the answer. For me, It wasn't easy but it was worth it. I wanted to be accepted for the 'real me' but I was scared. I think most "Out Men" know this feeling. It might SUCK at first but it is soooo worth it.
If I can be any help to a gay married man in my situation, I would invite you to contact me via the 'Ask Me a Question' form. I'm here to help. I've been where you are.