Hi and welcome!
How long have you been dating K? Does he have any other partners at this point or are you the only one?
There are a lot of great threads and posts on here that can help you as well as a great network of supportive voices.
Morethantwo.com is great! But also check out under Search, tag search... There are many tags there for I security, jealousy, coming out, etc that you will do d useful.
Good luck and much strength on your journey!