I feel like my dad is constantly disappointed by my speech and I don't know what to do.

I feel like my dad is constantly disappointed by my speech and I don't know what to do. I'm 21 and in college, studying to be a speech pathologist. I'm also a moderate-severe stutterer. I've stuttered since I was ~9 years old. My parents have always been supportive, but my dad has always been an anxious, impatient person. Throughout my life I've been in speech programs my parents have looked up. I participated in PFSP in Virginia to radically change how I speak, but it didn't work for me after the first couple of weeks. I explained to my parents, but my dad in particular likes to bring it up all the time as an example of how they've spent money on me that hasn't paid off. I get it, it was $9,000. I wanted to do it then and it didn't work out. Would it have been the same if they had bought a speech-easy and that didn't work out? I don't know. All that I know is that I'm still here with my speech. Like everyone who stutters, my speech varies widely in the way that I stutter. I block up, I repeat words, it changes from day to day. Right now it's manifesting more in an elongation of the first syllable, it makes it easier. My dad has told me four times now in the past three months that it's like "nails on a chalkboard" when that happens. He has also told me every chance he's gotten that my speech is really bad. He insists that I must be stressed or that I'm breathing wrong. He doesn't let me finish, he walks out of the room when I'm blocking, he rolls his eyes, and he does other things too. It *really* bothers me that I can't even talk to him, much less ask him to accommodate me in other situations. I love my dad. I'm never going to cut contact with him, which is what some other subs have recommended. I'm just trying to figure out what I should do. It hurts me when he does it, and it's been an ongoing thing for a long time. He justifies it a million ways when I try to talk to him, mostly by saying that he's trying to get me ready for the "real world" where people won't love me. I honestly think it just goes back to him being disappointed that I stutter. I just don't know what to do. I'm wondering whether anyone on this sub has had anything similar happen to them, and how they dealt with it.