Pregnant and husband might be cheating

So I was making a call on my husbands phone and he receives a text message while I’m speaking, I look down and his co worker is saying how much she loves him and putting winks and xoxoxo but keeps calling him Buddy. He says they’re just co workers but friends only at work. I never met her before, I’m 6 months pregnant with our first baby. I’m so confused, idk what to say or do.