exhausted...when is enough? ADHD spouse

I don't know where to start.   I feel like the weight is crushing me.  No one knows, because I keep it all together - I feel like I have to hide everything and fix everything.  I'm scared to walk away - what if it is fixable, and I know that he does really love me....could I be making a huge mistake?  I know that it would devastate him (not a reason to stay, but again, guilty me). 

But I'm afraid to stay - I read the stories where things don't get better, despite the best intentions.  I don't really want children any time soon, but if I did, I can't imagine bringing one into this environment - I parent enough already.  I don't want to be that person that had all the signs, and ignored them.  I don't want to put myself through more if there isn't an end. 

Please, I don't know what to do.  I'm at the edge, and I don't know the right answer.  I know no one can give it to me.   I can't really talk to anyone, as they wouldn't understand and its way to complicated and private anyway.   I feel hopeless, but I'm afraid.  I'm not willing to live the rest of my life like this.  There are glimmers of hope, but I don't know that they are enough.  How do you know if there is a  chance...or if it is time to walk away?