I've posted this before, but have a read. It gives some practical tips on how to be a secure person. It's work though.
Also, have you been in therapy or are you considering therapy for just yourself? You might also consider seeing a practitioner of Neuro-Linguistic Programming. Some of that stuff can be very good about changing the script you tell yourself in your head. Clearly, right now, your inner script to yourself is designed to keep you down.
Originally Posted by lost
I'm excited about the possibility of US having polyamorous relationships, where we find mutual lovers that we can share. This sounds like a great way for me to shatter some of my social anxieties, throw away fear and embrace love for humanity. (wow, I can sound corny)
This is a HUGE red flag to me. PLEASE PLEASE PLEASE do not consider poly relationships or other people
you're in relationships with as TOOLS to solve your own inner problems!!! It will only end in pain for everyone. None of that magical awakening or throwing away fear is going to happen if you haven't already dealt with it inside yourself first. An insecure person is going to feel insecure regardless of how much their partner bends over to make sure they feel secure. In fact, insecurities usually blow up and grow in such situations, even MORE SO if you're in a poly relationship.
NOBODY is going to break the cycle for you. NO RELATIONSHIP is going to break the cycle for you. The only way the cycle can be broken is if you own the fact that you are the only one keeping it going and then take the necessary steps to own the fact that you are perfectly capable of changing it.