Dealing with getting upset and emotional easily

I am a 23 year old female and I have had an increasingly difficult time dealing with disappointment and sadness. I have been like this as long as I can remember and have been criticized for overreacting to seemingly small issues often. My problem is that even the smallest rejection or disappointment can lead to intense feelings of sadness. It often happens when things don't go my way, no matter how silly it might be. I feel very strongly that whatever is happening is injustice and I burst into tears. No one can understand why this happens, least of all me. Does anyone else feel this way?If so, how can I go about controlling my emotions and outbursts? My feelings are very often uncalled for and even though I consciously realize them, it takes the same amount of time for them to pass.
On a side note, I worry that I have several symptoms of Borderline Personality Disorder. I have issues maintaining friendships and I feel like I am socially anxious. I am constantly upset by the lack of meaningful friendships and relationships in my life but I never really do anything to seek out new ones. In relationships I have had, I am insecure and clingy or avoidant and I have cheated. I have memories of being molested by my grandfather as a young girl but I don't know how it contributes to the way I am. All I know is I think about what happened to me more and more often as I have grown older. I have lived my life across three cultures and countries and will be soon moving to a fourth. I often feel like I don't really have an identity. I also have a strong sense of not having any special qualities or even any real interests. I always feel mediocre and that I've let down expectations of me as I was an intelligent child in highschool. I have started to make changes to myself now but I used to resort to binge eating and drinking alone to make myself feel better. I have had awful moments, one in particular, of drinking so much alone that I could have died of an OD. I have also suffered from episodes of depression in high school and university.

Please advise as I am having a really hard time understanding what is happening to me.

Did you write this when you were in a bad mood? Write it a good mood. I'm sure you've got plenty of good qualities. For one, you're intelligent. I have that impression after reading your post.

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I think the answers will be in your childhood.Yes,
you will know it was wrong,but children also make
THEMSELVES wrong as a person. Be good idea
to see therapist and work through what happened
in childhood--the way out is through,not around.
God Bless,
BLUEDOVE

Therapy can help, if you are not already in Therapy. You are smart, so you will succead!.