Hi L. ~
In response to your SSI benefits - You need to definately check with SS Administration. It doesn't sound right to me that you would lose your benefits just because you get married. Now, if you were receiving benefits from your ex husband, or a deceased husband or relative, yes you very well may lose those. My mother never remarried after my dad died because she would have lost his pension and she would have had to take her SS instead of my Dad's (which is larger). Finances are definately something to consider, especially at your age.
In regard to the house situation - consult an attorney about making sure you are protected in regard to your equity. Don't sell your house and land, then move in with this man without having your name on all the deeds/titles (house and land). I had an Aunt who made that mistake. She sold her house, got married and moved into the man's house. The guy was abusive, they got divorced, but because her name was never put on the deed/title of his house, she got nothing. (pre-marital property). BEWARE!
Finally - In regard to marrying someone at this stage of your life, with two teen boys at home. Being a step parent is a hard job. The teen years can be the most stressful and challenging as a parent. You don't say how the boys feel about him, about you marrying him or about moving. You might think that having a man in their life would be good, but they might resent him. You have been the primary care taker and they might not adjust so well. It could end up being a strain on your marriage, as well as hard on your childrn.
If you and your man are both devoted Christians, it shouldn't be too difficult to wait in regard to marriage. You can date until your children are up and out. He will still be involved in their lives, but they wouldn't have to go through so many changes (emotionally mainly). They could come to know and love him gradually. Of course, you know, that living together and having sex before marriage is out. So, be willing to sacrifice this part of your relationship for the time being.
This is all advice for you to consider. Only you know in your heart what is best for you and your children. Just don't make any rash decisions without thoroughly considering the possible consequences and without having all the facts you need in order to make an intelligent decision.
Best Wishes ~ K.