How do I make him take me seriously?

So I have been in a casual relationship with this older guy for a while. I’m 20 and he’s 26. He pursued me first and showed actual interest in me but as time went on he said he didn’t want a relationship so we just kept it casual. A few months ago, this other girl came into the picture. He wasn’t interested in dating her either it was just another girl he was messing with. Which of course hurt me but in this type of situation I know he’s not my man so I can’t get upset. He started out saying she is this 19 yr old girl who was homeless and he was helping her out by letting her stay at his apartment. It’s now gotten to the point where this girl is trying to date him and is extremely possessive over him. She’s still constantly at his house and is very controlling. One day it’s like he acts like he wants me and the next it’s like he’s with her. We finally talked about things a few days ago and he said Thankyou for being calm with him and he knows he confuses me but he is just going through stuff. I basically replied by saying I will not tolerate being a second option and I deserve more. He kept saying he truly does like me but he has real fear of commitment because he has trust issues with women and he said he doesn’t wanna f*** things up with me. But then, it’s been like almost a week since that convo and he hasn’t texted me or contacted me once. Like I think if you like someone you wouldn’t be able to go a week without at least checking in on them? him and I also work together so that makes it worse. I can honestly say I am hurt to the point where I feel sick to my stomach. I am angry and all I want to do is make him jealous. I know that’s petty but I’m tired of him playing with my emotions and basically I am asking for advice on how to make a man jealous and want you more?
How do I make him take me seriously?
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