My world is being rocked at its foundations

Hi this could be a long story but I'm going to keep it brief . Six months ago I met someone that I just knew more than I ever have in my whole life , that he was the person I want to spend the rest of my life with and/or love uncondiotnally . We are both 26, and met through a very close mutual friend of both of us. I've never felt this type of love before it's qualitatively very different to any thing else but it's also making me feel a rush of conflicting and sometimes scary emotions as a consequence I find myself wanting to distance away from it yet at the same time finding hard to do so. It's bringing out stuff I thought I got over and causing me to ask questions like : what does he see in me ? Maybe he's be better off with somebody else ? Am I good enough ? This isn't coming from him at all by the way , he thinks I'm amazing. These types of insecurities have never come up for me in a romantic relationship before , and it's making me feel like a crazy person. Has anyone ever felt this before ? What are the tools to cope with this ? I want him to be happy and have a good life more than anything because I genuinely and deeply care for him....