Boyfriend suddenly jealous?

Hey guys so I really need some honest opinions here regarding my boyfriend. I'm feeling confused.
First I'll start off by saying that I haven't been the best girlfriend since we've been together. We've be together almost a year and I admit I've acted pretty jealous and insecure throughout our relationship. I have been cheated on in the past and have severe trust issues as a result. I didn't mean to project these issues onto my new boyfriend but unfortunately I did. On many occasions I indirectly made my boyfriend feel like he has cheated on me or would cheat on me. I would constantly look over his shoulder and see who he was texting and what he was doing on his phone although he never had anything to hide (He is very transparent). Since the beginning of our relationship my boyfriend has never been jealous, and if he ever was- at least he never displayed it. He has given me his full trust since the beginning. He never questions me or felt the need to look through my phone. He's also told me he he doesn't care who I follow on Instagram or Facebook and I shouldn't care who he follows either.
However, since I let my jealousy and insecurities get the better of me, he has told me he is getting fed up with me not trusting him and he wants to show me how it feels to not be trusted in "hopes" that I will change. Recently I had went on Instagram and viewed a guy's profile who has a t-shirt company. My boyfriend saw the tab in my phone and got upset at me for attempting to look at it. I have never seen him get mad for something like that before, it was SO random. He's told me many times he is not the jealous type and doesn't care who I follow. So why did he get upset that time? He then made a big deal out of it and said if it were me I would have given him shit for looking at another girl's instagram. Is he just trying to teach me a lesson so I can see what it's like to not be trusted? Why is is acting jealous when he has never been that way before?
Boyfriend suddenly jealous?
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