Here is a mental exercise that will help train your financial sense:

Having a good reputation (for getting work done well and on time) and a little money in the bank gives you confidence. It's extremely likely that you will be alive tomorrow, and so it's a pretty safe bet to leave future you in a slightly better position so he won't ever have to make such moral compromises. If you think about it that way, it might help you get your gut feelings on board with your long-term plans.

Newp. Just a stranger with transparently reasonable advice!

A classic tale of a horny young man who can't afford to leave the stable girl but really fantasizes about making a break for the exciting new one willing to share him and be his side-piece, for now.

Advice:

(1) If they both knew about each other and you were supporting them both, you might get to have your cake and eat it, too without being a cad. If you were very lucky and very thoughtful and very trustworthy.

(2) Your plans were already doomed before all of this. If you left G1 for G2 (even if you haven't wrecked your ship already) then the most likely outcome is that G2 and you will both be miserable as soon as her life gets worse by having to take care of you. You need training, experience, and/or education so that you can be confident in pulling your own weight plus helping your partner.

I am not saying this to be mean. I am trying to give you good quality advice: Be prepared to pay full price for what you want from people. Be strategic and work hard so that you can afford to be a strong contributor to any relationship. If you are confident and generous you won't need to manipulate anyone or lie to get what you want because you will have real bargaining power to just ask, and real poise to be gentle and polite when you are rejected.

Your story is the story of a coward and a manipulator, but you could grow up to be something better, and I hope you do!