I’ve been cheating on my husband so long that I don’t even know if our child is his or not

My husband and the man I’m sleeping with both look kind of similar. White, dark hair, light eyes. My type. My husband and I have been married since 2008, and I had been sleeping with another man in 2007. Dates overlapped and blended in together. I don’t know when I was with who.
I’m thankful our son came out the way he did. I guess I’m more thankful I’ve been sleeping with a man with similar physical traits to my husband. No ones knows except my best friend, and she has secrets too so I know she’ll never tell.
I’m too scared to do a DNA test because I truly don’t want to know the truth. Our happy little family is fine the way it is. We barely fight, are good financially, and have a lovely home. I don’t want to ruin anything by having that test done. But I do regret overlapping dates and sleeping with my husband and boyfriend way too close together.