Depression is a serious condition, and yes, it can be genetic. Some of the symptoms you described (crying for hours on a regular basis, lack of purpose, self-esteem issues, anxiety) can be associated with depression. I would recommend speaking with a mental health professional, even if it is just your school counselor. They may guide you towards some helpful information regarding how to cope with/treat depression.

It sounds, too, like you aren't very happy with yourself. Do you generally like your life? Do you know your talents, and are you proud of your accomplishments? Would you consider you a "friend" of yourself? Do you treat yourself with compassion? Do you feel comfortable being alone? If the answer to these is "no," you may struggle with poor self image and a lack of self-confidence. When we don't have a very high opinion of ourselves, it's easy to base our sole happiness around another person. We feel high when that person is with us, and crash when they are gone. If we're happy with them, things are great. But if there is a rough patch, suddenly everything is in jeopardy, and your anxiety goes on ultra-high alert. We simply get used to having the other person fill us up, instead of working to fill ourselves up.

But that's an unhealthy way to live. It's not healthy for one person to be your source of happiness, and it's not fair to them to want them to bear that much responsibility. They say you can never be truly happy with someone else until you are happy with yourself. I don't necessarily believe that, but I do believe that relationships are a lot more meaningful and fulfilling when both people are solid by themselves and secure in themselves. That way, the relationship is balanced, instead of one person holding the other up.

So I would suggest taking some time to learn what makes you happy. What is your identity, aside from your boyfriend? What do you like to do? What are some activities/ hobbies you can do by yourself and get enjoyment out of? Building up your relationship with yourself, and learning to rely yourself more, will not only lead to a healthier and more fulfilled you, but will also strengthen your relationship because it makes you a more solid individual.

As for your boyfriend leaving- yes, he will leave, and it will be hard. It may hurt, a lot. But it sounds like you two are very close. And while you may not see him as often, good communication and frequent contact, while not the same, can help keep your bond strong. But a year is a long time away. Instead of worrying, enjoy the time you DO have with him right now. Build up positive memories while you have him here.