So many thoughts may be filling up in your mind, such as this can not be happening to me, or they can't leave me, we can work things out, etc. etc. If they are unwilling to stick around and try to fix the relationship then realize that hey are not worthy of you. Perhaps you took your vows seriously and they did not!
It is a sad statistic that one out of every two marriages will end in divorce, so you are surely NOT alone. It is a very emotional and draining experience to go through and when the divorce is not wanted on your part, it can be overwhelming. There are things that you can do to try and keep your head up and realize that you are worthy of someone to truly love you for who you are and not give up on the relationship.