Female Colleague(29) used me (26M) to get her husband(32M) jealous.How do I pull out?

For a background , me and her work at the same place and we text a lot.I happened to be a very good looking guy and am used to female friendship, even though I,m not the one to start it.

So, seemingly we became good friends and visited her home after she invited me as a friend from work.Hubby was there and we both hit it off well.Over time we used to hang out together and he keeps describing to me how beautiful she is and how smart she is and stuff like that.On the other hand she constantly puts him down or have arguments in front of me.

Slowly I started playing along and started flirting with her in front of her hubby, she responds in kind and he sits there doing nothing.Both of them like me, and he keeps inviting me home. But I feel hes sidelined and I dont want to hurt an innocent guy, as they keep arguing in front of me and she ends up speaking with me more than him and he sits in a corner brooding.

So, am planning to not hang around with them anymore.How do i decline being invited to hang around?, because she keeps texting me about coming home and taking her and her hubby out and he seems to not mind being the invisible person in the conversation.

Also, Is this a common phenom with good looking guys and avg couples being friends and the couple shares their issue with this third person?.Something like a mid life crises?.