((((((Confused)))))) Welcome to SoberRecovery. First, take a deep breath - you're in a safe place with people who care and who can relate to what you're going through. Second, please make your way to the Nar-Anon forum, which is the forum for families and friends of addicts. You'll get some wonderful support there from people who are dealing with similar situations. Please be sure to take a read through the "stickied" posts at the top of that forum too - there is a wealth of helpful information there. You don't have to do this alone - in addition to an online support group, there are face to face meetings through Nar-Anon/Al-Anon with real live people who also have an addicted loved one. If you need help finding meetings in your area, please let us know.
Any addict, including your husband, can stop using if they are really ready to do it. It often takes the loss or near-loss of things near and dear to get them to that point. Opiates such as heroin can be difficult to detox from without medical support, but you don't mention any particularly erratic behaviour or psychosis - the mood swings are common and may last for a while before he stablizes. Your husband would be helping himself by reaching out to a support group such as Narcotics Anonymous - I tried to do it alone in the past too and failed, but with the help of NA I've been clean now for just over a year.
Welcome again, Confused - we are listening and we do care.
Sometimes I go about in pity for myself, and all the while a great wind is bearing me across the sky.