Advice for a jealous lover?

[DC4319]

So, I've been in my current relationship for over 6 years. He's been the only person I've dated ever in my entire life. I'm happy with the relationship but the only thing that's truly killing me is the fact that I can't handle him sexting and having, and sometimes acting upon, sexual interests with other people, which he enjoys doing. I have told him I didn't like it and he understands, but he really can't help himself, especially around his friends both online and in person. He's a real people-pleaser and loooooves attention he can get from non-creepers (even gained a reputation for it).
It's eaten away at the back of my head for months, years even, to the point that I'm an insecure mess. I tend to lash out at him now if he hints having sexual urges with someone else, I get controlling, invasive, angry, etc.

I know 'dating' isn't necessarily a true or deep-relationship and you have to be open to things, but I grew up to that teaching that if you found the person you want to commit to, you give it your all, which I felt I have. Now I just feel like that effort was for naught, that I'm now just some person to keep around til the next best thing comes around.

What do I do?
How am I supposed to see things so I see just him and not his sexual tendencies?
How do I move on and get back to loving him as a whole? Start feeling like I'm his "one-and-only"?
Or do I just drop it and move on with my life?