My fiance and I have been living together since January 2016. A month after, he was sent to work on a job 600 miles away, and we only saw each other on weekends — which was also split up between time with his kids.
His ex does not allow me at any family events, like sports games, or wants me around at all. Four weeks ago, I was put on medical leave, and he has changed drastically. His relationship with his ex has gotten a lot stronger. He has disappeared and spent the night over there three times and not told me, answered my calls or texts, and then is angry with me for being upset when he returns.
He was supposed to come home for good this past weekend. Everything seemed good the night before. Saturday & Sunday, he did not answer my calls or respond to my texts. He showed up at 8:30pm Sunday night like nothing happened, said he was on a “soul search” and tried to be all lovey dovey with me. He left the majority of his belongings in a “storage unit” and took an Uber home. His Uber record shows him leaving from his ex’s house.
His first day back, he went to work. I called about one hour after he would have been off and asked him if he was coming home (I was honestly surprised he answered the phone). He said, “of course.” Two more hours later, I called and asked him if he could give me a time frame cause I had already cooked dinner. He jumped down my throat and said I had a bitchy attitude and to calm down. He still hasn’t told me where he was or what the heck is going on.
I am so very sad and frustrated and not allowed to express my feelings. i don’t know what to do. I’m trapped here because I have no where else to go right now. I love him and would really like to know what is going on. It hurts that I’m not even allowed to ask.
LemonVibe 
I’ll be brief and blunt… Run away. As fast as you can.
Ok, the longer nuanced response, but please do not lose sight of the suggestion above.
I know that the actual solution will be much more complicated. It will take time to untangle your lives and living situation. The fact that you are out of work on disability further complicates all of this. It will not be easy, but please understand that the situation you are in is NOT healthy. That the Ex won’t allow you to be around the kids is NOT an acceptable condition of the relationship. Not if you are engaged. That your fiance disappears without notice with some regularity is not acceptable behavior. You need to find a way out of this engagement as quickly as possible.
Deflection is always, ALWAYS a sign of an abusive behaviour. As an outsider looking in, he is inattentive, manipulative, and sneaky. These are in no way whatsoever your fault, and the fact that he’s blaming you for his actions (or “lack thereof”) are very telling of the type of person he is. This is not a relationship you should be in. Is there a benefit to keeping you around, money or anything? Because you have to ask yourself why he’s with you while trying to sneak around your back. I honestly would not give him the satisfaction. Do yourself and favour, and try to end things ASAP.