Okay, back at a real keyboard now...

Although I can never say "I know how you feel" because I was raised in a half-Christian family in the UK which is barely religious in the first place, I would say many of the things you say sound familiar to me. I go to a Meetup group called Beer Not God in my area and we often have attendees who went through similar experiences or are even still in the closet to their families. If you are looking for like-minded folks checking Meetup.com to see if there are any atheist groups meeting in your area could be a good start. There may be other ad-hoc groups - you might find folks via other larger orgs like American Atheists who have local chapters. Another "code word" to look for is secular humanists or just humanist societies.

A year or so ago we had a visitor from the UK who runs a group called Faith2Faithless. They are in touch with some "underground" groups that help people escape their religions - Christians, Muslims, Mormons, all sorts. They also do interviews with former religious people and you can watch some of them here:

https://www.youtube.com/channel/UCh-ZVAxsok4FUxG75830AZg

or check out their Facebook page here:

https://www.facebook.com/faithtofaithless

Anyway, regarding some of these things your family is saying to you - I couldn't agree more how theists put the burden of you on you. For them they can just say "It says in the bible" or "It's god's will", but for atheists, we have to have all the answers in triplicate to every single crazy question - and they won't believe or understand anything you say.

I'd put the responsibility back on them - if I should believe in a god why should I believe in you. There are thousands. Prove yours is the real one. Prove it. Everyone has a book or mythology. Everyone says their god is the one because their book says so. Challenge them to think about how they would be if they had been born in a different country or had different parents.

As for the atheists are bad people - ask them why they are good. Because god will punish them if they aren't? Or are they hoping god will reward them if they are good? Point out you are good without either threat of punishment or promise of reward. Good without god to me is a very compelling argument when explained and sold properly. 10 to 20% of all Americans manage not to murder, rape, steal, adulter without reward or punishment from a god, and that's just America. In other countries it is far higher. It also doesn't even begin to account for the people who are just pretending to be religious and don't actually believe anything of what they do or say to fit it.

Anyway, hang in there. There are many fellow atheists out there who are willing to back you up and support you. It may not be easy but if it is really what you want you can find sympathetic ears to talk to, many of which will have similar experiences. We atheists need a secret handshake or something but let me tell you I'm rooting for you even if, as I mentioned, I had it pretty easy with my background. Definitely check out meetup.com if you're in the US. Or ping some local or national atheist or humanist orgs to see if they have local chapters. People like you are all over and can help ease your transition to being fully out. You may have to live with changed relationships with some relatives or friends, but I don't think you'll ever be alone in your situation!