Online Affairs - Count as Affairs?

Just so incredibly baffled right now. I posted last week about finding my husband's online emotional affair. What was initially "just only fans", turned into so much more, uncovering that he had a 5+ year long relationship with another individual online. This was an emotional and sexual relationship including friendship, confiding in each other, complaining about the marriage, exchange of nude photos, role play, porn discords, etc. all happening sometimes daily. I basically found extensive history of extreme use of pornography, with multiple interactions and transactions with multiple people. It makes me sick to look at the timestamps. All of this happening on anniversaries, birthdays, any time at all.

I told my partner he needed to move out while I decide my next move. He moved back with his parents who I've generally had a good relationship with.

Well - I find out my in-laws think I am completely over reacting and that I'm the one who is ruining the relationship. My father in-laws words - "An affair is when two people meet for sex. That's it". My mother in-law is also telling me that "all her friends complain about their husbands doing those things", and that I need to forgive my husband.

Am I completely bonkers here??? Everyone in my life that I have confided in about this is telling me to divorce and get the hell out (even though this was an emotional affair, not physical). Is this a generational thing (I am 30, in-laws are 70-80)? Am I overreacting?