One of the hardest, yet most crucial, aspects of life we learn is that you sometimes have to let go of one thing to have another.
If you continue as you are now, you run the risk of losing both women. I've seen it happen so many times a person waffles, wanting one while relationship to another. Things like that can go on for a while but eventually some little error brings it all to light and then things get bad quickly. So many times I've seen the paramour walk away when his/her lover finally became available in every way. You see, its one thing to be in love when that requires little to no commitment and altogether another when one faces the knowledge that she is the cause of a relationship ending. That guilt can quickly erode the positive emotions. You already know her weaknesses and strengths. You see mostly the good in the new woman, yet your statements indicate that there is a nagging in the back of your brain that being with her would present another set of problems that may be worse than what you have now. Rather than hoping the new relationship will help you find happiness, I strongly urge you to move away from that woman!
Yes! I know it will be difficult and that you are so much needing affirmation that you would feel great pain if you stop seeing her and find the help to get you where you need to be with yourself.
Though I am not a prophet, I fear that if you continue with the new lover, your self esteem and need to feel loved for who you are rather than what you do will become even a greater problem and happiness will elude you for years to come.
When you find the way to love yourself , truly love you in a good way. You can then do what it takes to make your current relationship be what it should be!!

honestly... do u want to be wih someone who would drop another for u? if they can do it for u, they can do it to u as well. if ahe want happy ahe should leave him, with or without u. she doesn't sound like a good choice to me.

as for the relationship u are in now, end it, she deserves better than someone who is lukewarm towards her and who loves another. u are doing her a huge injustice.

I do take what you mean on board but the issue I am faced with is that if I go for the new one and it goes wrong I have lost my best friend

I find it beyond all comprehension WHY you would stay with someone you're not entirely happy with? Sounds to me like you have simply 'settled' for your current partner. Huge insult to her, I would hate to find out that I was someone's insurance choice, someone's 'company' whilst they wait for their something better. I don't know about the second woman... but you sure as hell don't deserve the first one.

dump your current gf, and enjoy the single life if you feel like that!

It's all about taking chances.

go to switzerland

...sounds simular to chocoholics scenario, you just want the sweetest to savour!