The process of letting go is hard

tnr9 I think of a quote in the 'Attached' book that says something like "never underestimate the power of an activated attachment system". It's one of the most painful experiences I personally have experienced, feeling like a live wire just buzzing with anxiety, and this hollow doom just bellowing from within you, and waves of fear crashing around you.
Another quote from the book says something like "dependency is not a choice, it's a fact" - if B has been assigned a position in your head and heart as an attachment figure that represents love and validation, it's going to be a painful process for you to go through if he is not a reliable source of either of those things, through no fault of his own.
The way to move toward secure is through the consistency and dependency of an attachment figure, creating that new experience of healthy attachment that can show you the goodness of your own dependency and help regulate you... if we're consistently surrounded by people who aren't able to do this for us, I think especially too if we have unconsciously assigned someone the role of primary attachment without even making a conscious decision to do that, I think whether we like it or not, it is going to have a negative effect on us in an attachment sense... I want to give you a great piece of advice but I don't know what I could offer. Are you in therapy, or do you have consistent attachment figures in your life who can meet your needs emotionally?
The way that I have moved more towards secure from AP/FA is by having compassion for myself and surrendering to defeat with friendships with people I am in love with who also trigger my attachment wounds, because I know for me that it just slides me more over to the AP end of the continuum and away from secure and I feel that parenting myself also means being firm with myself. This may not even be what you want, and you have the right to decide different for yourself, but I could not do what you are doing, I would experience the longing to be crippling.
I hope whatever I have said has some helpfulness to it, even if it is just something that helps you realise what you want because it contrasts what you want

tnr9 As far as I'm concerned you are absolutely not a failure. I'm glad hearing the perspective of someone secure helped you see that struggling to let go is normal. I think one of the primary differences between secures and anxious are that anxious people tend to think something is wrong with them a lot of the time, when in reality, secures struggle with a lot of the same attachment issues anxious people do, they just don't make it harder on themselves by believing they're broken because of how they feel! I've done this a lot too, and I still do sometimes, but we need to stop it because we're just human like everyone else and thinking like this hurts! Try to remind yourself that we all struggle, it doesn't make you less, you're awesome, and if it's hard to believe yourself, just think of how many friends and family think so! They can't all be wrong