Need advise

Found these in my husbands phone from his coworker / friend who we always hangout with my husband states she’s just someone who comforts him emotionally helps with advise when we are having problems I love my husband so much we are expecting our first baby who we have been really trying for she will be born in July. I trust my husband when he says he has not had sexual w her but I have all these thoughts trapped which are triggering my depression I need some advise has anyone gone thru similar scenario how did it end HELP