How can I prevent my partner from selling the house we live in with our 3 children.

We've been together almost 20 yrs, not married, 3 children ages, 18, 15,10. Lived in NJ, 5 yrs ago he came to Fl with our son, stayed with my sister while he looked for work. I had given him my savings of $15,000. I was in NJ with my 2 daughters hunting online for homes that he could go see. I found this home and we agreed to buy it. I wasn't on the mortgage or deed because I was still in NJ. When I came down here we were so happy, getting along fine and never thought about a separation, forgetting about my name on anything pertaining to the home. Now he wants to sell it, saying it's his house and kicking myself and kids out. We had this verbal agreement that it was our house together, as a family. Do I have any recourse as far as stopping this? Can I sue him. If it wasn't for my money and finding this home we wouldn't be in Fl. I haven't worked in all these years because that's how he wanted it. I suffer from MS,my 10 yr old has Downs Syndrome big changes are hard to handle