Are you sure it's a demonic attack? Your husband is in despair and you have OCD. No matter which of you is feeling stronger at any given moment, the best you can give the other is lighter fluid to put out the fire.
OCD is a need to stay in control. Despair? Well, despair is giving up entirely.
I'm not sure this is demonic. (I'm not sure it's not.) One thing I am sure of is it is time to give up. Give up on both -- trying to control and thinking there is no answer.
And then what? Give in!!!
Give in to God. He's the one in control. Give in to trusting yourself and give it to him. Your way isn't working. Your husband's way isn't working. There is only one Way and his name is Jesus. Give into him!
And, yes! Heaven knows I get OCD. (I grew up with a dad who has it, and it has changed everyone of his kids -- all six.) When you give in -- give it to God -- you will undoubtedly take it back. It is habit, and this is what habit does to us. BUT, you will notice when you do that, and when you notice it, given in again. Give it to God again. And again. And again, again, again! There is no shame in how many times we have to give it back to God. The shame comes when we will not, once we notice we took it back. So understand, you will be giving it back to God hundreds of times per day at first. That's okay. Keep doing that, and then you notice it's only 100 times per day. Then only 90, then, and then and then. Because he's the one who can change us, not us! The more time he has to hold us, the more he changes us to something good, something loving, something trusting that HE IS IN CONTROL! Not us!
Us in control is fearful. Him in control only works all things to our good and his glory.
Give in!
And then watch God does his thing in your life, your husband's life and the world you live in. This will never look like something you controlled, but that is the beauty of it -- HIS control is far superior! And it is a lot prettier than what you're experiencing now.
OCD is not your master, nor your faithful companion. God is! Give in to him! (And if it is demonic? Well, guess who has control over demons too. Keep giving into him and let him deal with demons.)