R..
I do see red flags all over the place...mostly on his behavior...but don't give him fodder for use.
You can agree than when a couple marries they are to become one under Christian teachings and are responsible to each other and for each other. You stopped giving her money because they chose to start living as if they are married before the wedding. (Just make sure that she can finish her degree so if the money is for tuition please make sure she can pay to finish her degree and she can support herself when she does kick this guy to the curb...especially if there are kids involved by then.)
I am guessing this finance is not a practicing Christian (and maybe your daughter isn't any more either and afraid to tell you). So, he is looking at your views from a different upbringing and angle than you are...you cannot force him or your daughter to live up to your Christian guidelines if they are not Christians.
You can love your daughter and make sure she knows she can always come home (go re-read the Prodigal Son parable). Don't cut her off, don't lecture, don't preach anything but we love you and want to see you and spend time with you. Step back, she is 20...
Hopefully one or more of her good friends will cut through and talk with her about him and his controlling ways. I tried with a good friend about her fiance who was a total loser. She was in love and got very angry with me and every single friend who tried to talk to her. We were all in her wedding and cried not tears of joy. She is now a single mom and we love and support her as still her best friends forever...it was hard watching her walk through it when we tried to warn her but we all still have her back. Be the parent that has her back even when all the fallout is over.
Pray for her behind her back and love her with nothing but love to her face. Hugs!!