Discouragement over these obsessive thoughts

I am discouraged today.  I am suffering and tired of being anxious.  Right now, all that I have learned and all that I am afraid of has been greatly disconcerting.  I feel like giving up and let nature take its course.  My thoughts are about infidelity.  Sometimes the thoughts are easy to deal with.  At other times the thoughts are so bothersome that they are anxiety-ridden and cause me to be frustrated.  I have anxiety about things that do not concern me.  It looks to be of great concern but because I have been taking such a great interest in infidelity the anxiety disappears, if only for a minute.  Then it comes back again. I have a hard time during those times and I need help.  Maybe God is trying to help me through those issues but what?