How do I stop feelings of unreasonable jealousy & extreme insecurity?

I think the challenge here, as you mentioned, is that your self-esteem is low and it's hard for you to feel confident and loving towards yourself. I would encourage you to look at how you value yourself.   

Often in these types of situations that involve jealousy, the underlying issue is about the jealous partner's insecurity.

And so there is an opportunity that is presenting itself from this problem. The opportunity here is that you can begin to value yourself, learn to self-soothe when you feel distressed and appreciate what you have to offer someone in a realtionship. You can start to believe and trust what your boyfriend says - that you are beautiful and loveable.

All the best.

The problem is, when we tell ourselves we are unattractive, uninteresting etc two things happen - first, we feel insecure and miserable; second, it can become a self-fulfilling prophecy - that is, in my conviction that I am unlovable I may behave in ways or say things that encourage others to see me in the way I see myself.

It may be helpful to think of that critical voice in your head as just a part of you - not all of you. Are there other voices in your head that have different things to say? How can you strengthen your relationship to those parts - the parts that give you confidence and belief in yourself?

Often that voice in our heads that is telling us negative things about ourselves has developed as a misguided attempt to help us. That part of us may believe that telling us negative things will motivate us to do better, achieve greater things - the equivalent of beating or yelling at a small child to get them to be ‘good’! This strategy can be quite effective (the child may indeed become ‘good’ - that is, behave in ways that are socially acceptable - in response to being spoken to harshly) but at a great price - the price of our self-esteem and confidence in ourselves.

You might try the following exercise:-
Expect that you will need to repeat this many times - remember, the harsh critical voice has become stronger over years of repetition; to create an affirming voice of equal power will take many repetitions too.

• Imagine that you are a compassionate, wise mother, looking at two children. An older child is telling her younger sister that she is unattractive etc (add your own words here!). The little one is crying and feeling sad.
  
• Step in as the ‘good parent’ and gently tell the older girl that it's not OK to talk to her sister that way. Give the younger child a ‘mental hug’ and tell her she is beautiful, and that you love her. Explain to your ‘inner children’, from your wise adult perspective, what real beauty is, and how different it is from what we see on television or in magazines. Teach them to notice the qualities they have that create attractiveness - kindness, a good heart, taking care of themselves as well as others. Tell them stories about women who have been extraordinarly ‘beautiful’ in our culture - women of courage and passion who try to make a difference for the better.
  
  

I have the same problem. It is really hard. One practical thing I find helpful is to have at least one day at home, no tv, no magazines and if you really must watch something to stop you going out of your mind, choose a cartoon ( not real bodies) that portrays healthy or not stereotypically ‘ hot’ characters, and download it, so you don't have adds telling you to be beautiful or have perfect skin or bigger titties, god I hate adds, they have singlehandedly made my body dysmorphia 2 times worse.

i personally choose South Park or Simpsons, futurama, Harvey birdman or so etching of the like so I am not being constantly subconsciously reminded that I look shit. 

Also a good idea is to controll the lighting, if your feeling self concious, but don't want to stop your partner watching tv then dim the lights or turn them off, so you don't feel like he will look at the tv, then at you and back at the tv comparing… Well, that helps me anyway….. Good luck

I understand just how much you want to stop these feelings of jealousy. But stopping feelings doesn't work. They just go deeper and come out in other ways. It helps to know though that they are just that, feelings, and that you probably developed these feelings at some point in your life, even if when you were very young because at that time you peceived something was  a threat to your survival. Feelings are neither right nor wrong. They just are. It's how we relate to our feelings that causes us the struggle.

Maybe you could enquire into these feelings when you notice them and ask yourself what is it that you are feeling underneath the jealousy. It might help you to get comfortable with the feelings and almost like you are conducting an experiment, try and look at them with a detached sense of interested curiousity and ask yourself how can I support myself right now while also acknowledging that you are having some difficult feelings.

Also, you could practice allowing yourself to take a breath and breathe into the difficult feelings as they arise and see if that helps you relax a little around the difficult feelings you are experiencing.

There are many more things that can be done and I hope you find that this challenge becomes a good learning experience for you.

Good Luck.

I would really recommend talking with a health professional about this sort of thing. If this is a very long-standing habit it will be hard to break easily. In my practice we often use Acceptance and Commitment Therapy (ACT) to help people learn to handle difficult thoughts and feelings such as the ones you mention more effectively so that they can live a more vital, more meaningful life.

Another option would be a book that whilst it sounds like it is just about body image it is more than that - http://www.goodreads.com/book/show/13436398-living-with-your-body-and-other-things-you-hate - you could read a bit on the Amazon website or in a bookstore if they have it and see if it sounds helpful for you.