So would I be wrong to do this?

My ex called me and said he wants to visit me and basically Netflix and Chill despite him being "engaged" to a married woman. He said they have an open arrangement.

I am completely over him and don't want to slide back into old habits especially when I really like the new guy but the new guy has other options he's entertaining. So I don't know if I would be wrong to sleep with my ex or not.

I certainly see why people just cut off their exes but I can't seem to cut him off because we were always good friends and I thought we could be good friends again. But he admitted that he can't really be in person with me without kissing me.

This is such a sticky situation and I don't know what to do. My mind and heart is saying don't go there with him again but my downstairs area is saying do it.

I feel like it's not fair to the new guy even though he's talking to other girls. I would feel like a straight up slut to sleep with my ex and then him.
Updates
1 y
I've decided that I am definitely not going down that road with him again. If he wants sex with someone he can either get it from his fiancee or from someone else. I am not stooping that low again. Plus it's not fair to the new guy I'm seeing.
So would I be wrong to do this?
Post Opinion