She can't have her cake and eat it too. She's banging another guy on the side and having the financial benefits and security of being with him.

OP if you're listening to this, dump that bitch you deserve better, let that other dude pay for their apartment. You are now a young bachelor with a good job and the world is your fucking oyster. Also much better this way especially seeing as she was your first and only serious relationship. Hang out with friends, drink, cry it out, and bang as many hotties as you possibly can and you'll feel like a million bucks. You're not worthless, you're being too hard on yourself and blaming yourself for everything, stop that shit. Buck up, grab your balls, leave and don't look back.

She doesn't get to cheat and then become the victim. She's not the victim in this and from your post it sounds like you sugarcoat her behavior not yours. She's a cheating bitch and you being bipolar doesn't suddenly cancel that out. You need to hire the most vicious divorce attorney and leave as soon as possible and leave her with as little as possible. Stop letting her gaslight you because it will only get worse, put your foot down and for once in your life, love yourself and put your happiness over hers. From everything you've said here, she is definitely abusing you, taking advantage of you, and treating you like a little slave. Believe me you can find much better.

Grab your balls and get the fuck over her man. You only live once and this is not going to be the mother of your kids.