Husband is doubtful of me

So my husband and I, along with our 3 kids all live with my in laws. My husband thinks me and his dad got something going on. Which makes me really sad and upset that he would think something disgusting like that. His mom thought so to long time ago which hurts me even more. Two weeks later(Yesterday night) my mil showed me photos of my fil and them went hiking on a trail. She kept swiping and swiped and saw a photo of my FIL naked. Caught us both by surprise and she apologized to me. It bothered me and made me feel uncomfortable. So I told my husband about it. Now he feels "weird" around the house. And he said I should've kept it to myself. I told him he's the only person I talk and tell things to. I literally don't have any friends or so I talk about my personal life so that's why I told him because it's bothering me. Idk what to say anymore the fact that he keeps thinking I got something going on with his dad. He said he's been thinking this for 4 to 5 years now but didn't know how to bring it up to me. Just recently, my husband open the door wide to let my kids in the room and my FIL walked by while I was still pumping milk. I was embarrassed. I didn't know what to say. So then my husband said that I didn't act or do nothing and say there must be something going on. I'm really hurt and don't know what to do anymore. I feel like even if tell him there's literally nothing, he won't believe me.