I Am Suspicious

I am married for the second time I have two boys by my first marriage, my husband and one of my sons went to the swimming baths on Saturday, I wasn't in the mood but after they had left I decided to follow them, when I arrived I got changed and swam about for a while but I didn't see them I thought they had changed there mind and had gone bowling, it was about 25 minutes when they came out of the changing cabins along the side if the baths, they looked shocked at seeing me, I didn't think anything at first, then I thought it doesn't take that long to change only minutes, when we got home I asked why so long to change clothes, they seemed evasive, and I thought no they wouldn't be doing anything sexual, then I thought back to short while after we met and became intermate he asked me to try anal sex I thought why not, I loved it having my dirty shit hole poked, when we porn its always a woman taking it up the arse, I don't know how to approach the subject, is my husband bumming my son.