Husband wants another DNA test

So me and my husband split for a couple months. In that time we were still hooking up but I did sleep with another guy. (I was stupid) we did a DNA test when our baby was small and it came back as 99.9999% my husbands but now that our baby is getting older he’s looking less like my husband. So, the other day he hinted at another DNA test. I don’t see the point in it since the % was so high but I’m not offended, I put us in that circumstance. What would you do? Get another test or trust the first one? It costs us $250 if we do it. (Which we can afford but would rather not pay)