Friend zoned

Ive been with my boyfriend for 6 years we have 2 kids. In november we had a big argument that did make us take a break he went to live with his dad. Coulpe days later we talked and got back together. He didnt want to move back in with me and the kids so he lived with his dad. Until his mam let him stay in the caravan she owns at holiday patmrk with it being winter he only skept there but spent the yime after work with me until late on the night this has gone on for 4 months. I messaged his step mam asking if they could have the kids on the weekend so i could suprise bf with date night. She asked why when we are not togrther and bf is single. He didnt tell them we got back togrther after the argument. I explained to his step mam we are together have been since the argument and he spends all his time with me buys me stuff valentines day and sex. She said he is single and just doing what a single person does. Pretty much she says he is just sleeping with me thats all and he is single. I sais no he isnt and sent her screen shots to prove we are in a relationship. Well it didnt go well they rang bf after work and he admitted weare in a relationship and they areso angry with him to the point they disowned him. After all what had happened i was annoyed and upset but love him. He didnt tell them we was together incase we broke up again. So last night he said he just wants to be friends and co parent the kids. I feel like its my fault if i didnt say anything everythingwould just stay normal. But i feel like he used me and hoping each side wouldnt find out what was going on. He was my best friend before we dated and now i cant just go back to being friends. His family wasnt annoyed that we were together it was just the lying he was single. And just want to he wasnt messaging orfucking behind my back he saw us as in a relationship and he is loyal. I just dont know what to do