Are we supposed to stay?

I know I love him. I know he knows he made a mistake. I know he would never intentionally hurt me or our family. I know if I wait he’ll be with me until I die. 2 - 7 years and only two weeks in. We’ve been together a little over a year and we were planning our future. He says the only reason he didn’t marry me before is because he wanted to let me make the choice. He knows my beliefs are strong and I only want to marry once. I’m 33 and I already said if it wasn’t him I’d be done having children. I come from an extremely conservative family and fear losing everyone if I stand by him through this but I can’t just stop loving him. I have never felt so broken and alone. Any suggestions? I haven’t told anyone in my life and his mom and sister are my only support. What am I supposed to do? Why would god give me this man just to take him away?