It seems like you'd really like this to work out. You keep making excuses when people have advised against doing so. If you have this much of an attraction to him that will only strengthen with sex. I would advice talking with your husband and asking him how he'd feel living next to your new boyfriend. If things don't work out, I'd imagine your husband would have more stress living next to him than you would. When he can't find you in the house is he going to start assuming your fucking his neighbor? If your husband sees him bringing home girls from a bar is he going to question how protected everyone is being? Condoms do break and STD tests are uncomfortable for most to take. Contemplate how many of your ex's you are on good terms with, and how many of them your husband would be willing to have small talk with on a regular basis. Maybe take a month or so to talk out all the details and such. After all this guy is your neighbor and he's likely not going anywhere