Jealously

So I've been with this guy for 4 years, at the beginning I was never jealous of what he did or who he'd talk to, we both would talk to people but after a while he started getting jealous, extremely jealous and well after he became jealous, I started to become jealous as well, but like super jealous! I never had this problem with anyone nor did I have this problem with him until he showed me he was jealous!
Now I do have my reasons why I should get pissed at the things he does but sometimes it goes way too far, I want to trust him but our history doesn't allow it! But I really want to go back to how the way I was ( not jealous) Anybody else dealing with the same ??