Done with his flooding

After almost 15 yrs of a rocky marriage and 2 kids (one of  whom has ADHD), I fear the flooding my husband experiences is going to end our marriage.  I’ve tried to tolerate it.  His defense is that it only happens once in a while so I shouldn’t hold that against him or carry it as baggage in our relationship.  But, I can’t.  I’m not built for this.  He is a wonderful man with a kind heart and all the morals and good values any wife would look for.  And when he’s not held hostage by his quick temper, he is helpful and fun and attentive.  BUT, when something happens to set him off (even something accidental) he becomes a different person.  Someone I don’t like.  His tone becomes loud and bitterly sarcastic.  He will yell and curse in front of our kids.  I don’t know this man.  And as quickly as it happens, it’s over for him.  But I am left feeling bitter and unhappy and drained.  My feelings of love have been diminished.  Even when he’s being nice, I can’t help thinking “it won’t last, he’ll have another outburst soon enough.”  He has ADHD.  I also believe he has what Melissa calls rejection sensitive dysphoria.  I’ve seen him get rageful when our son doesn’t feel like hugging him.  It’s terrible.  He doesn’t even realize it.  He is taking ADHD meds.  But he won’t do the important work involved in therapy/anger management to really get this in check.  I am very conflicted and keep fantasizing about leaving him.  We don’t have trust issues or affairs.  We are not physically abusive to each other.  I know in my heart that if he really worked hard, he could change.  But, I can’t make him work.  He went to therapy for 2 mos, and stopped because of 1 thing the therapist said that pissed him off.  I keep thinking, “am I ready to leave?  One more outburst and maybe I’ll just fly out the door in a fit of anger?  WHAT WILL MY LAST STRAW ACTUALLY BE???  Or have all my straws already been broken?  Maybe if I say I’m leaving that will finally wake him up?”  Sorry for the rant.  I am seeing a therapist and working on “me.”  But my feelings about my marriage remain negative and sad, even when things are peaceful...because they are never peaceful for long.