taking on to many work task,none is completed.

My DH is the work work work freak,and I love that he says it builds his self esteem, but, he is taking on a little more than he thinks he could handle,he cannot even complete the first job that he started a month ago, got paid "big" already, and now he is on to the third one,I am the second of these 3 jobs he has going on and it's heavy,,, (and on top of that he is working at a company for someone else),,,.Meaning,he has dropped 2 car transmission's on the ground to fix,one of which is mines, and now just today he took on a next job without having finished the first two,and he is the only one doing these jobs with little to no help!,I need my car!!!he is taking tooo long to hand it back to me,and now the man who paid him already of which I'm sure wants his car too,and now a third man is going to have to wait.DH thinks that he could do do do all this in a little time b/c he is so distracted all the time and don't know how the clock works at all.I tried to explain to him that he could become a little too overwhelmed and he said to me nooo!!I could do it,I even explained that when he has all that work going on and task are not being completed it could put a hurting on our marriage,and sure enough it has.It has created more mood swings,more anger,more resentment and so on.I keep trying with him over and over again.He tends to get frustrated easily when something he is working on don't come out right and then he starts to feel pressure at failing at a task.Has anyone experienced this type of behavior with ADD spouse please share.