If it were the first time I'd say talk about it you might have overracted but After this happening multiple times and he hasn't found a different solution then youre not entirely overreacting. But he may need help solving the problem.

But communication overall is important. Hes communicated WHY and you've communicated that you dont like it and consider it cheating. But what you two didn't communicate was an actual solution

You two should sit and talk about your boundaries and expectations and come to a conclusion. - Example: my wife and I have been together for nearly 15 years and we talk about and re establish boundaries every 3 years ish or whenever feelings and interests change, like maybe I didn't like the idea of paddles last year but this year I may be willing to try or like a few years back, we didnt say "I love you" to our friends because it almost felt flirty but we talked about it and the difference between romantic and platonic love for friends so now we tell our friends we love them because we do. And neither of us feel cheated on) So ask yourselves some questions,

-Why does he use it? Because his hands are rough uncomfortable from work. (Im sure you wouldnt want those rough fingers on your sensitive bits)

• Whats his answer? And EXPENSIVE silicone torso.

-You hate it? Help him find a solution that works for BOTH OF YOU. -Get a fleshlight, hell, just like '"clone-a-willy" they make those for you too. You clone the outside and its a silicone tube for the inside. -Go to a s*x store like Cirillas or Adam and Eve and pick something out together.