Trust is the problem, not tarot.
This is a serious problem. This is a marriage, and that means you should not have to hide who you are. When you try to keep things secret, then you create a situation like that of a volcano going off. It's all hidden away, till it's discovered (and it WILL be discovered!) and everything explodes--his anger at you for lying and doing "evil"--your frustration with him for not accepting and making you sneak around.
So. Change the situation. Don't let it go that way. This isn't going to be easy, but the other way--sneaking and hiding--is cowardly and will lead to worse results. You must, instead, pray, meditate, prepare and confront him.
So you need to sit him down and tell him, "You're my husband, and I love you. And I don't believe in hiding things from you or lying. That's not good for our marriage. I am not doing anything wrong or evil with tarot cards, I am doing what God wants me to do. I have prayed and meditated about it, and I know that this is a gift from God that I need to use. There is nothing wrong in it. I will be doing this. I don't ask for your approval, but I will not stand for you or anyone else condemning me for doing it or passing judgment. I will not stand for you or anyone else throwing out my cards or books or trying to intervene or change me. This is part of what I do. This is part of who I am. You don't have to watch or participate, but you MUST trust me one this. As the woman you love, as your wife, you must trust me first and above all others, including your parents. If you can't do this, if you can't believe that I know what I'm doing, that I know good from evil, and that I'd never do evil, then we need to see someone."
Don't try to convert him, don't try to justify the use of tarot cards. If he believes them evil, then your arguments are going to fall on deaf ears. The one important argument here is this: You KNOW in your heart that Tarot is NOT evil, and what you're doing is approved by God. He either believes you, or he doesn't. If he doesn't, then that is your problem. If he can't take your word on this, what else can't he take your word on?
I don't doubt your husband's concern or belief is genuine, but it's also clear that your need, your spiritual calling here to use tarot, is also genuine. If it wasn't, you could just say, "Well, he doesn't like it so I won't do it." If your need is strong enough that you're sneaking around, then it's time to come out of the closet, be open and honest, and offer a trip to counseling if differences can't be resolved.
One caution: be sure you pick the councellor ahead of time. If your husband insists on arguing that the cards or evil, says he won't let you do it, then say, "We've an appointment with this therapist on Thursday." And you go to that appointment whether he comes with you or not. Otherwise he'll try to get you to some minister who will want to convert you on the topic of tarot cards. You need someone who will see that this is not about Tarot, but about control, fear, faith, etc. And it could apply to almost anything. Tarot is just the "flashpoint" of difference.
Either your husband puts you first, either he can say to his mother, "I trust my wife and you will not criticize her," or he can't. If he can't, you've a larger problem than tarot cards.