How to protect myself and my children if my name is not on the mortgage?

My boyfriend of 7 years and I are currently in a "lease with option to buy" situation. We have been renting this house for 2 years and are now ready to purchase. My credit is really bad due to a foreclosure on my previous home I owned with my ex husband. We had been working on improving my boyfriend's credit score so he could qualify for a mortgage, which finally happened! We are both cosigners on the lease, but only his name will be on the mortgage. I worry that he could kick me and my kids out on a whim after he buys this house though. I pay at least half of the bills, and no way could he have afforded to live here for the past 2 years without my income. We want to get married but can't at this point due to his crappy insurance coverage and my special needs' son who needs to be able to keep his benefits. The original $5,000 down payment for this house 2 years ago came from ME, so I feel I do have legit interest and investment in this house. Is there ANYTHING I can do to protect myself and my kids? I trust my boyfriend, but I can't predict the future. Can my name be on the deed at least? Thanks for any help!

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