If it makes you feel any better, i've been turned down by men who "don't believe in" non- monogamy, but i still feel good about myself. Even if you were to start a second relationship there is no guarantee it would work out, for reasons that have nothing to do with non-monogamy. So take it easy on yourself.
To add to what SG said, if you're seriously thinking about running away from your life, then maybe that IS what you need to do. Start over again with a fresh slate, but remember said fresh slate is within you, not for other people to determine.