I have been keeping an eye on your sitch and following along from afar.
Yes, your H is in one heap of a mess! The problem is, as I see it, is that your allowing H to get under your skin and you react. I know, I know living with him and his ongoing childish antics is no picnic at all. My heart melts for you as you confront them every single day. It has to be mentally and emotionally exhausted.
I would suggest that you make the following changes:
-No more responding to or initiating any texts when you BOTH are in the house. It will force H to stop his silly PA behaviors from his dorm room -Each time he whines about getting old, look at him and say I am sorry to hear that you're still struggling with this and hope you will find some peace with this some day soon. I love it and embrace it wholeheartedly. The way I see it, I means I'm collecting wonderful moments and memories that make me who I am today. And I cannot wait for some more exciting revealations. It is my hope that you'll be able to work through whatever it is that's blocking you from enjoying life to the fullest." -Step in your own true power and speak up for yourself if H speaks to you in a disrespectful way. "H, I feel you are speaking to me in disrespectful fashion and I won't tolerate it from you. This stops right now. I am willing to listen to you when you are calm and show me respect. Thanks for listening" -I think it's time for you to really send hard truth darts when H whines about parenting or complains about sons. Yeah, H most probably will send you angry texts from his dorm room. Do NOT respond to them at all. Silence is golden
Stop texting or responding to texts while you both are in the house. If you need to say something to H, you'll have to schelp down to his frat dorm room. You'll train him to talk with you when you ignore his texts. He will learn that if he wants or needs something, he'll have to *gasp* talk with you in person.
