Hey Mel! You're stuck in quite the confusing situation, but hopefully I can help you out a bit.
I completely understand your desire for freedom. Once we turn like 19 or so, we really want to seize control of our lives and do everything. That's so beyond normal. But I think you're being impulsive with this decision. Ask yourself this: Are you running to something or away from your problems? A change of scenery can be great. I feel like you may get the most benefits from putting off the move for a bit. Tie up the problems before you start over in a new location.
The first point is that it's really hard to get a job without a high school diploma. I know that not having one doesn't make you stupid. You're obviously more intelligent than like 60% of the people in my graduating class. But potential employers don't see that, they just see that they have an applicant with no high school education and that will work against you.
So I really see waiting as a chance for you to get your GED. Its really hard to go back once you have a lie build up, but ignoring the fact that you didn't graduate won't change anything. The truth will come out eventually. So I really feel like it's in your best interest to talk to your parents and tell them the truth. Then you can show them how you're growing up and maturing by taking the class and exam and getting your GED. That will make it much easier to get a job once you move.
You can also continue working while getting an education. And that will help you learn about managing your money and you'll build up an even better reference for when you do move and need a new job. Plus, you can save so you'll have savings when you move. It sounds like you're staying with your parents. Are they charging you rent? If they aren't, ask them to start charging you money. Only they can really just be holding it until you've learned what it's like to pay bills. Having to pay rent will teach you how to manage your money to make sure you have enough to cover your expenses. Plus, you'll really be saving money. And it may help you get a better idea of what it will be like when you're on your own and have to pay rent and such. If they're already charging rent, ask them to increase it. Sounds harsh, but that's really a good way to save money.
Onto your sexuality, telling them is completely your choice. If it's really bothering you, you can choose to let them in on it. Really, your sexuality is how you express part of yourself. Keeping that from them may very well be pulling you guys apart. It's impossible to feel as though your parents love you and accept you for who you are when you know that they don't even really know a huge thing about you. For you to be happy, you'll likely want to be with a female at some point. Faking relationships with men isn't satisfying, it's merely a way for you to satisfy society at the expense of your happiness. But I also support coming out when you're ready. Maybe you'd rather wait and tell them later on. Personally, I'm bisexual. But I know I'll avoid the confrontation of coming out to my family until I meet a girl I want to be with. But I'm also satisfied with my relationship with my mother and know telling her won't strengthen it. Every relationship is different. If you feel as though coming out will make you happier, do it. Really, it has to come out eventually. Short of being constantly unsatisfied with your love life, there's no way to hide being a lesbian.
As far as your friend goes, all you can do is continue to be there for her. You can decide to share your feelings with her. But keep in mind that she may have really fallen for the person she is engaged to marry. So you may put your heart out there and be hurt. Sounds very pessimistic, doesn't that? I'm just being realistic. Unfortunately, life isn't a movie. So hoping for the best is wonderful. But you also have to be aware of the possible negative outcome before making your decision. That's how you make an educated choice that you won't regret later on. So now you know why you may want to not tell her. We can be optimistic now! She could have the same feelings for you. But more importantly, do you really want to live and always know that you kept that hidden and missed your chance to be with someone you love? Really, it's for you to decide. But I personally would not be able to live with not expressing my feelings.
I feel as though you're running. This isn't you moving onto something better. This is you trying to escape your past. But honey, the past is set in stone and not going anywhere. What you can change now is your future. Before you can move on from your past, I feel as though you need to resolve the ongoing conflicts. Show your parents how you've changed by being honest with them and then following through and getting your GED and saving money. Don't leave until you're ready to not go back. And I don't think you'll be ready until you're leaving to go to something instead of running away from everything.
Hope this helps. :)
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kid, I wrote back,
all lovers betray.