How to test whether a boyfriend is cheating by SMS?

First of all, I don't agree with you. Besides, he is a married man. What can he give you? Even if he loves you, can he marry you I suggest you break up with him now. It's you who will keep getting hurt in the future.

If you insist, let me give you an idea. You can send him a short message saying: You are sick or have an accident now, let him come to you at once to see if he will really come at the first time.