Beyond tired

I have tried and tried to be patient with my fiance who has ADD but I am tired. Tired of the disappearing acts, aka lack of communication (we currently do not live together), tired of the excuses, he is swamped with work to do (which is code for don't expect a peep out of him for who knows how long but he has plenty of time to be on Facebook all hours of the day and night posting useless things or responding to anyone and everyone that posts on there. I have been catching him in lies lately, ofcourse he denies everything and tells me I am over reacting. Tired of one minute he is sweet, caring and the next minute is cold, distant and acts aloof. He comes with two kids not to mention which I have been more than understanding about him tending to them when he needs to, they are older but I encourage him to keep a relationship going with them.  He will not go seek out help for his ADD and frankly I do not believe he thinks other than time management issues with work commitments that he truly has any issues. Last for now I am tired of all the big grandiose plans (for him and I, ie. big trips, purchases ) he loves to brag about infront of his kids or my family when he and I can barely maintain our relationship on a daily basis, and frankly I can't see any of these "plans" happening. I have suggested more than once that maybe he and I just is too much for him to be involved in now and every time I bring it up he gets mad and says quitting us would be a big mistake. I am tired of feeling alone in the relationship and feeling like if I want to address anything with he and I I will be walking on egg shells for weeks after around him. Very confused right now..really on the fence about he and I.