I hate being so angry at him all the time, but his forgetfulness is getting dangerous!

Hi all, I'm new to this group but after reading so many of the forums I feel so much better already. I finally feel like I'm not alone! 

That being said, my husband has not been formally diagnosed with ADHD however he displays ALL the symptoms. He gets super hyper-focused on something he working on (i.e. training for a marathon, exercising, etc) and everything else fades away to a blur in the background. He remembers my birthday (most times) but he's forgotten our son's numerous times (he's 7 months, we're planning for his 1st birthday and he can't remember the date). He gets distracted easily (he flips through tv channels at warp speed!), he forgets everything we've ever talked about, he can't hold down a job for longer than 6-10 months at a time, he's aggressive towards the baby, passive aggressive towards me, and depressed, and it's messing with our marriage and our family. 

When we were dating, the thing I fell in love with the most was the fact that he was so wonderfully different. He has this macabre and morbid sense of humor which, at the time, I found new and fascinating. He was always interested in doing new things, and his energy was electric. Now that we have a new baby, however, his morbid sense of humor is not nearly as funny as it used to be. My patience level has dropped significantly because I'm spending all the time and effort and patience on the new baby and not on him. His lack of concern for safety with the baby has caused huge rifts in our marriage. We talked about safety with the baby countless times, things like clipping him into the car seat correctly (because often times he only clips him around his stomach), or being gentle and not shaking him around ("we're just playing!" he says, "he likes it!"), or being aware that the baby doesn't have any teeth yet so he can't chew on large pieces of fruits and veggies, however all of our conversations are for naught. The baby fell over when he wasn't holding him correctly and started crying. I ran over to see what it happened and his response was "oh he's fine, he's a warrior. Warriors need to learn how to get hurt and get back up." He's only barely 7 months!!

He gave him a piece of cucumber to chew on while he was teething, and the baby bit off a piece of it and almost choked on it. We talked about it and said no more until he has teeth and we'll have to find a better way to give him what he wants. Yesterday he gave him cucumber again and he nearly choked on a piece again. I don't know what to do because I love him and I want to spend my life with him, but I'm getting very worried for the safety of my child.

We started couples therapy, but he's already thinking of ways to get out of it. I really just don't know what to do.