My boyfriend's 3 kids are living with me

My boyfriend has done some really stupid shit and because of that he's looking at 5-8 years in prison. And he's most likely going to get it too. I've been with him almost two years and he has 3 kids and they all lived with him. His oldest is his 14 year old son then 10 year old daughter then youngest is the 4 year old son. Me and my boyfriend had actually talked about finally living together this year but he went to be stupid! His kids had to watch the police put him in handcuffs and take him away. They tried to get their mom to come get them but she didn't want them. After the little family they have they asked if I wanted to take them. If I didn't they were being put in foster care and most likely split up. I said I would take them even though I don't have a whole lot of space. I've spoken to my boyfriend over the phone and he thanked me but I was pissed at him for putting us all in this situation and his kids are probably traumatized. I can't even help him with a lawyer because I have 3 mouths to feed now. I have a 2 bedroom so I put his ten year old daughter and his 4 year old brother in one room because they're closer in age. Plus his 14 year old deals with night terrors and sleep paralysis so I think that would scare the little one. And his oldest I put in my room and I moved into the living room. I'm really stressed out and but I've had to get a mindset that this us where they are gonna be for the next possibly 5-8 years. I'm trying not to show my stress so I don't scare them. I've never been a parent so I'm winging everything. My mom is coming down this weekend to take the kids to do something fun to get their mind off everything. His youngest son has also become very clingy towards me. He's always at my leg and wanted a hug or cuddle or me to play with him. I've been trying to make sure he feels affection. His daughter has been crying and I'm trying to comfort her and his son just completely locks himself in the room and doesn't come out. I'm hoping my mom doing something with them will help them feel better... I'm hoping I'm doing an ok job caring for them. I don't really have maternal instincts so all I'm able to do is wing it

Edit: Thank you guys! I'm really trying my best. I am planning on applying for government assistance. I was also told I could put their mother on child support. Idk though because that women isn't just a deadbeat mom. She is crazy and violent and I don't want to tick her off. I rather not be involved with her at all. The kids do have insurance through the state so I could probably find them some therapy that accepts. They haven't been back to school yet, I'm sending them back Monday. A little worried about how thats gonna go but luckily school will be out next month.