Does your wife know all of this? Not just the banter, but your true desires?

She knows I’m bisexual but she has no idea that I’m hot for her son. She would not accept it at all.

I recommend that you keep your distance, then. When he's old enough he can make his intentions clear. It's playing with fire in any case. In my years of experience, I screwed things up a number of times by letting my libido, my cock, think for me.
That's what you're doing, possibly, letting your libido think for you. Your wife may wonder about this already; in fact, she must have put 2 and 2 together, knowing you open mind. How could she not have thought about it?
Stay away and maybe some day something will change, but remember that you're thinking with your cock. Only if and when you get a signal from your wife that it is OK should you make yourself available. You are a role model, too.
Do you jack off in front of your wife and vice versa, by the way? If no, then you know it's hands off the offspring.
If yes, she's already imagined you and her with the boy, possibly.
Just brain storming here - - be careful because this is a risky situation and he's definitely teasing you. Again, he's teasing like a prick teasing teen woman.

If you wife would never be “ok” with you being sexual with her son you need to quit playing with fire and gasoline at the same time. There are a few million other humans on the planet that you can find an attraction for and who don’t pose the obvious threat to your marriage that this boy does. You will be set up to look like the predator and he will look to be the innocent victim if something is discovered. Don’t knowingly put yourself in that position.

I agree it would be best to leave it alone. Sounds like trouble.

UPDATE: Maybe this coronavirus lockdown is making everyone a little crazy because something happened last night. I heard him in the shower and I was loading the washing machine and had to get my dirty clothes from the hamper in the bathroom. I knocked on the door to see if it was ok that I came in to get the clothes. He said it was ok and I went in the bathroom. Of course all I could think about was his jokes about me watching him shower and him flat-out telling me that time to ‘just come on in’.

We have one of those sliding doors in our shower. He was in there and I couldn’t see anything through the door. I went over to the hamper and grabbed the dirty clothes. As I was getting ready to leave, he pulled open the door to the shower!!! He was standing there naked, the water still running over him. He smiled and asked me if I could get the dirty clothes from his bedroom to throw in the wash. Now he could have just told me that without opening the door. So he tells me this and I’m standing there, I can’t help but look at his hot body. It was really hard to make any eye contact at all when I had so many other things to look at. I told him I would get the clothes for him, then we just stood there facing each other. I didn’t try to leave and he didn’t close the shower door. This lasted about ten seconds and I just sort of froze and didn’t know what to say or do. He was smiling a little and looking at me and then he looked down at his cock and then he looked back up at me and said ‘thanks’ and I just stood there for a little while longer, then I turned and left the bathroom.

WTF? It’s obvious that he was showing off to me. Now I know for sure that he either already knew that I think he’s hot OR he just assumed I’d be interested in him since he knows I like men. Part of me is wondering what would have happened if I hadn’t left the bathroom. I didn’t try to hide the fact that I was checking him out either. He knew I was looking at his cock and his body because I did a lot more than just glance at him quickly. He’s been in his bedroom all day since I got home from work so I haven’t seen him since the incident. I figure that it’s unlikely anything bad will come of this. It’s not like he can tell my wife that I did anything wrong because he is the one who opened the shower door. I don’t know what to say to him now when I see him again.

All that being said, I got what I wanted! He is such a stud. He’s not skinny or anything, he has just the right amount of chub on him. So sexy. He has a small cock but his balls are very big. Well he was soft so I don’t know how big he gets when it’s hard but it definitely was on the smaller side in general. He has a nice bush which surprised me because I know a lot of dudes his age usually trim their pubes down to almost nothing or else they shave completely. But he seemed to just let It go and it was definitely sexy. I cannot believe this happened. I have wanted to see him like this for so long. I had seen him naked once briefly in a changing room but I only saw his butt. I’m a little worried about how he will act towards me now but I’m also a little excited about how he will act towards me now.

I don’t see how it could turn into a problem. Especially if I wait to get the dirty clothes from the bathroom until I hear him in the shower. If he wants to open the shower door and give me a look, that’s on him. It’s not like I’m being weird and creeping on him. I don’t think it would hold much weight for him to say ‘Yeah I opened the shower door to tell him something and he saw me naked!’ Of course I’d see him naked. As far as going further with him...I know doing anything more would be a bad idea but honestly I don’t know how I could ever turn him down if he suggested it in any way.

Well I’m pretty sure he knows that I want him. Especially now. When he opened that shower door, he left it open for a long time and it was obvious as hell that I was checking him out. Since then, he’s been acting normal towards me.

do you have to keep using the word sluts in every post?

I’d feel like I’d scare him off by suggesting that I shower with him or just whipping my cock out in front of him. As of now, I don’t even know if he is attracted to me in some way or if he just likes showing off his goods. Plus if I make an obvious pass at him, he could tell my wife. At the moment, I haven’t done anything I can get in trouble for. He’s the one opening the shower door and standing there naked in front of me. I’m just standing there talking to him.

offer to wash his back for hum

That’s a good idea actually.Just to be able to touch him like that would be amazing.

Just reach toward it and ask "Can I help you?" He'll know what you mean, and will probably say "Sure" or similar. Grab his cock and jerk him off, slow and easy, and the ice is broken! Good Luck!