You need to get help if you value your marriage.
That's literally the entire point of her post. 
She knows she needs help because it's affecting her marriage, so she's asking on here for help and how to seek help. What a redundant reply!
OP, like any addiction it would help to clarify for yourself the feelings behind why you do this, like what void it's filling. Then you can try to find other ways to get that satisfaction. Also using simple tactics like cutting off your own credit cards and only using debit cards with a low limit could be a way to tie your hands.
Identify your vulnerable times too. Do you shop more when you're tired or anxious? When you're home alone at night? Note those things and find ways to avoid them.
Cognitive behavioural therapy can be useful for addictions too. A counsellor trained in CBT could help, and there is an app I have used called Thought Diary (probably better ones out there) which is good for writing down your thoughts at the moment of crisis or decision making. Then when you see in writing what your thought processes were, you can try to find strategies to help in those moments you feel weak.
Sometimes just a radical change can help too, like taking up a new sport or going on a trip somewhere. Or signing up to volunteer to help the less fortunate.
Opening up in an honest way and asking for support from your husband is good too. If he's a decent guy he'll be open to supporting you how he can, like rearranging bank accounts etc. But you may prefer trying to solve it in your own first.
Posting here shows you already know it's a problem which is the best first step.