I was asked to come to the police station

I got a call from a police station to come for an interview. I had a rocky relatinship with my ex boyfriend. His car was stolen and was returned after 5 days. The police never found out who did it. It happened half a year ago. And my now ex boyfriend accused me on several occasions that I had something to do with that. And a couple of days ago we had a fight, and I jokingly texted him sms saying something like that: "Will you drop about the camry already? What's a big deal, you got it back. I just needed a ride to the lake to have sex with some guy from his work because I thought it would be hot to do it in your car." I never did take the car. And I don't know anybody from his work I just wanted to annoy him. And he called the police and told them I might have done it. If I refuse to go for an interview can they arrest me based on that text? If I go to the interview what do I say about the text? I can't afford a lawyer, can I request a public solisitor at this stage? Please help me.