My husband doesn’t trust me

I feel absolutely sick right now. My husband apparently found condoms in my car and totally went off on me!! I don’t know where they came from or whose they could be. I have 2 teenagers that are in and out my car very frequently and I explained to him that they could belong to the kids and he refuses to believe that!! I have never given him any reason to think I would cheat, I come home straight from work, never go out to functions by myself, and usually stay home 90% of the time. It hurts so much that he doesn’t trust me and it is even harder because I am going through some health problems and I need his support! I don’t know what to do!!!!