Time, consistent *new* responses from him.....and *I*, personally, would not ever be able to be comfortable unless he was in therapy to address the controlling-ness.
My stbx was very controlling/possessive also. Very. We went through many *calm* periods after Dday when we were (supposedly) working at the M and he would 'back off'....but I retained those same feelings that you described. (In my case, stbx always *fell off* the non-abusive wagon within a short period of time.)
I talked about this scenario with a counselor a few years ago, and I'll describe it a little bit because what occurred to you is very similar to what I went through.
When stbx placed me in situations such as you described, I felt *guilt* or as if I had done something *wrong*. These feelings popped up because of stbx's response to my not answering his call. He would make me feel like I was *neglecting* him or he would be accusatory and act as if I hadn't answered because I was doing something naughty. (yea, he only projects a teensy bit)
Anyway. Counselor said to take a second and recognize what I was feeling. I'm sure you know what I'm talking about, PP. That *anxious* feeling in the pit of you tummy, right? The loss of thought about ANYTHING other than calling him back ASAP so that you don't get *scolded*. And then he said to think about the situation and ask yourself *why* should I feel guilty and afraid about this?
It's one thing if your WS had said "I'm going to call you at 3 about suchandsuch' and you got into the shower at 2:59:59, kwim?
But if you just randomly got into the shower and he just *happened* to call at that time.....well, it's no big deal and you don't have any reason to feel guilty because you didn't do anything wrong. You're allowed to schedule your day and decide WHEN you're going to take your shower. And if WS picks that time to call...when you are in the middle of doing something else....well, that's just bad timing on his part and he can leave a message or shoot you a text and you can get back to him when you're not busy.
I think my counselor's point was that I'm *allowed* to be busy and I don't *have* to be always available....and there's not a darn thing wrong with that. The dysfunction is WS's to own....because it is wrong of him to expect you to be available for/to him 24/7. (I say that in a general sense because there will be situations where immediate contact is necessary).
It's very hard to break the pattern. But as long as you are able to recognize it......and your WS is working to understand how to respect that other people are *separate* and have boundaries that need to be respected, your *anxiety* should fade over time.
Now about the text exchange. This may have been a convo to have face-to-face or by phone. His comment could be taken as dismissive....or it could just be shorthand for what 20W said his response should have been. (in my case, if I had gotten a response like that, it would have indicated that he was, like, *granting me permission* to have missed his call, kwim....and then when he fell off the wagon a few days later and freaked out on me, he would demand *credit* for the previous times that he had *overlooked* it 
)
IMO, your response was too submissive and shows that you're still stuck in the *old* mindset.....because again, you didn't miss his call because you were doing something wrong. If anything, YOU would have had the right to be upset with HIM if he had gotten pissy about it, IMO.
So this is a situation where time, all by itself, isn't going to make this go away. You'll have to use the time to actively re-program yourself.....and I think that you'll only truly end up losing that *anxiety feeling* if you see that he is also actively working to overcome his previous *it's all about me* attitude.
(I got kinda rambly on you....sorry 
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[This message edited by gonnabe2016 at 12:44 PM, August 25th (Sunday)]
In my effort to be *concise*, I often come off as blunt and harsh. Sorry, don't mean to be offensive.
