Waiting for boyfriend to reply my text or to text me.

We just started a relationship couple days ago. I get really anxious when he doesn't text me. I would know that he would be off work at this time but still, he has not send me a text. Sometimes, it would take him hours to reply my text and during the wait I get really anxious. I would think about why is he not replying my text, what is he doing, and can't he text me when he's having a washroom break at work. I know where is trust issue right now because we just started. It's also because it's my first time being in a relationship with someone who I met through an online-dating app.
When he doesn't reply my text, I get so anxious that I can't do anything. I can't focus at work and my heart just drops. When he does reply and everything seem normal, I would be happy again and do what I need to do.

I started this habit when my ex-boyfriend cheated on me and there was never a closure. I don't love him or care about him anymore but then it created this insecurity within myself. I know that this current guy I'm dating is loyal and faithful and he values relationship. I need some help!