Gosh, this is a rough one for me. I feel for you. This is bad timing to have Grandma do what she should have done years ago. It's going to be hard on you and the kids. What is your boyfriend in jail for? This is very troubling. I would sincerely question whether I wanted to be with someone that was doing what it takes to get put in jail---- drugs, selling drugs, stealing, etc. I get that desperate people do desperate things but if he has the character to be involved in these activities, do you really wan this help raising your kids? No joke on that question. Kids become what they see.
I would absolutely apply for aide to get some type of education or job training. Something specific that pays well. paralegals make really good money and the program is 11 classes and intern time. With grants you can get it paid for. That's just one example. You have to do something like this to break this pattern of needing others to take care of you (including a boyfriend you clearly can't count on to be there because of things like he just might be incarcerated . . . and now he'll have legal bills, a record which it makes it harder for employment, etc.) This is the only way I can see your life ever getting better.
Your Grandma is trying to be responsible. She knows she's enabled you to have a childlike life by bailing you out time and time again., And then sees the pregnancy with a guy she may not love who's now in jail as just the final straw. Your life is your own project to fix. I want to reach through the computer and give you a big hug and say "YOU CAN DO IT,"
and it will make your grandma so proud if you do. And your kids? They will see that mom can do what it takes to be there for them and provide for them. So that they'll grow up to be hard workers. No, I'm not talking about piddliy jobs but a real career. So, think about what you want to do, apply for aide and go do it. Work a part time job during this. Your kids will understand. Apply for govt. assistance to help with child care of the baby, ditch the jail bird boyfriend who will do nothing but hold you back, get section 8 housing to live in (do not bring boyfriend or a new boyfriend of some sort to live with you) and turn your life around. Take some temporary fixes to get a long term better place.
You really have a big choice to make right now. This is a turning point in your life. What are you going to do?
I think your grandma sees history repeating itself again, another bf arrested and in jail. She helped you out a lot with your ex and your twins when it happened the first time, and like you know yourself, she probably thinks it's time you took some responsibility for yourself. What kind of men are you dating that they get arrested and thrown in jail? That's no way for you to live, or any of your kids, and being pregnant he needs to be a lot more responsible too, like I say, I don't know what it is he did wrong, but you automatically grow up and think twice about things once you have kids.
Your grandma sounds like a wonderful lady, and you have been so very very lucky to have her and her support, and no, I don't think she's going to do anything silly like resent your new baby or anything, I honestly think she's just thrown her hands up in the air and had enough. That's great your bf has 2 jobs and working hard to support you, when he gets out of jail he needs to keep at it and you guys really need to get your own place, just keep trying, it'll happen. Good luck!