Feeling anxious around my ex boyfriend

So me and my ex broke up almost a month ago and we agreed to still be friends, but it's been really hard on me. I can't really be myself around him anymore bc I've been feeling anxious and insecure when we hang out. I'm still heartbroken over the breakup and I'm still trying to process everything. Even though our relationship ended on good terms, I don't know if staying friends w/ him is such a good idea anymore. I don't feel that he is affected by it at all bc he's acting as if nothing happened. Idk if he genuinely doesn't understand how I'm feeling or if he just doesn't care. I desperately want to move on, but especially since I don't feel like I got complete closure as to what lead up to the breakup, I can't move past it no matter how hard I try. It's gotten to the point where being around him for too long makes me feel angry and super sad at the same time. I've been trying really hard to make our friendship work, and he may think things are completely fine, but I don't feel like it's really helping me. I thought being friends w/ him after the breakup would help things get back to normal and help me to move past it more quickly, but I don't think it's helping. It's been affecting my other friendships/relationships and my daily activities because this is always in the back of my mind. I am always feeling really worried and anxious about how my ex feels about our breakup and I have lingering questions that I'm hesitant to ask him at this point. I'm just wondering if I should just end our friendship so that I can create some distance to clear my head and move forward without him around to remind me of what happened. Or if there was another method I could use to try and still be friends w/ him without feeling anxious, angry, or sad around him all the time (I'm 20 years old, if that helps at all).

Any advice is greatly appreciated. Thank you for taking the time to read all of this :)