Long distance is rough

I know I'm not the only one who is in a long distance relationship in this world, and that is comforting. I am 22 and he is 27. I am currently living in China and my boyfriend is in the US. He is in the military, and I teach oral English at a university. We met while I was in college. He was friends with some of my older friends. He has seen some of the hell I have been through in my life, and he has been an anchor. It's really hard sometimes though. I knew it would be, but there are days when I wonder if our differences are too much and if my mental health issues will be too much for him. We have different personalities and different mindsets, but we have things that bring us together in a way I never thought I could imagine for myself. Having FaceTime and calling when we can has been good, but there are days when I ache to be with him. We have been "talking" for a little over a year, and dating for the last 4 months. He plans to visit me a few times while I'm here until January, but I wonder if it is a good idea. He has to pay for the passport, visa, and tickets. I don't have the money to help and it's killing me. He says wants to come to see me because he loves me, and I believe him, but I'm a poor girl. I can't get it into my thick skull sometimes that it's worth it to him. That I'm worth it to him. I've been in two other relationships, and they were good, but my first ex who was my best friend before we dated died, and my second ex broke up with me because he thought it was better for us to be just friends. My current boyfriend is so understanding and thoughtful and I love him a lot, but I can't help but wonder if he deserves better... Anyways. I was just ranting. I don't know if I'm asking for advice on LDRs or how to suck it up on the whole money thing, but if you read the end, you're an incredible person and I hope you have a wonderful day.