Insecurities getting the best of me..🙄

Whit

Little back story, my S/O has moved to another state to pursue his career and get a head start for us, soon I will be moving out there with him and hopefully getting engaged. During the time we've been apart my mind has been racing with thoughts of him leaving for good, cheating, dropping me completely and everything bad under the sun. He always reassures me when I bring this up, I trust him 100% I just can't seem to get my mind to quit obsessing about this. I also feel as if he thinks I'm accusing him which makes me feel worse. Anyone with advice on how to manage this?