Hello and sorry to hear that this might be happening to you. In amateur author Dorian Wright's book "20 Years Gone: A Divorce Story", many of the ways are revealed in which they found out that their spouse was leading a double life. You might want to pick up a copy and review the examples, as it covers details regarding text messages, strange behaviors, and more (it is available at Google Books and Amazon).
I hope that you find the info that you need to put your conscience at peace. Keep us posted.