Your help with stepkids...please!?

SKids here for 6 weeks. Husband is happy, defensive and sensitive. He didn't budget for the visit and never does. I have gone to the grocery store 3 times in two weeks. He paid back all but $150. We're on a tight budget and have a child together, too. Over the weekend, we found out that the ex is texting and calling and asking about our home, telling them more lies and having them lie straight to our face as well as call us names (by text) - but eat our food, etc. How do you handle these teenagers and when is enough enough? One is already 19 and has a job, I said no this year, but she's here, how long do we continue to send for her?