Hey Stewie, I think it's great you are posting here and asking for help - you recognise that this is not good and that is a big step in the right direction.

I have been on the other side in that my husband has been jealous about male friends/acquaintances in my life - fact is I have never cheated on him in 23 years together. Notice how I didn't say I have never looked at another guy? Well the fact is I am human and of course I have noticed attractive men - but that is quite different from pursuing them.

I like Rose's idea about fact checking and challenging your thoughts and feelings. When we explored my H's jealousy he believed if he felt something then it must have grounding eg he felt jealous so there must be a reason. Except there wasn't. I would have had to have only female friends in order for him not to feel jealous. He didn't want to restrict my choices of friends and so he chose to work on his own reaction rather than restrict me.

I think that you say you don't feel good enough is the basis of these feelings - this is good you recognise that. Have you done any work on your self-esteem/self-compassion? If not then this could help. You can do this yourself with self-help (lots of resources online) or in therapy, and your could include your bf with this, this could be a good way to help strengthen your understanding of each-other too.