On only one of the subjects you brought up: you have the right to the attention of the person you're with when you're with them. They should be emotionally available to you and shouldn't be carrying on a text convo with their other or telling you constantly about their other relationship, even if it is the biggest thing going on in his life at the moment. Everyone has rights in relationships and this is one of them. Without that you don't really have a relationship.
On another, you have something really scary to do. Since it's not working out for you I suggest you call a four-way meeting where everybody states what they want out of this situation. You get to talk about your feelings and why you have them and what you other people to (hopefully) do about it. You get to say you feel left out and used and you need more attention from your husband. That's not unreasonable. His other will still be there tomorrow or next week and you have the right to ask for, and get, more of his attention.