Whether the email used to set up that iPad is still valid or not makes no difference. It's the Apple ID used when the iPad was set up. As long as you can remember what that email address was, you can use this link for a reset of the Apple ID Password --> If you forgot your Apple ID password - Apple Support
To prepare the iPad properly to give to your husband, after you've signed back in, use this link --> What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
If you still cannot recall the email address you used when you set up the iPad (the activation lock page gives you a major hint, like y***********@hotmail.com), then find the original purchase receipt from when you bought the iPad with the iPad serial number on it, taking it and the iPad to Apple for help.