Husband on instagram...

So we don't do social media, but every now and then I google my husbands usernames and today I did it and he popped up, on Instagram...to my amazement he has a profile and comments on girls photos. Alot of them. One said "jesus babe you're sexy and beautiful in anything you wear"....what the actual fuck. And another "you should come see me and I'll give you something to bounce on"... I'm furious. And dont have a clue about where to start. Been together 12 years just got married in September. I'm doing some thinking before I approach this. Apparently he doesn't know you can see anyone comments on there. Any advice would be greatly appreciated...and all of the women he follows are either half naked or fully naked.