You've decided that this person is not the sort you want around. It happens. Breaking things off is not as difficult as you think, although it will require you to go through some unpleasant situations.
There are two ways to go about it:
The Direct Approach
Ask to meet her in a public location, such as a cafe. I personally think that this would go easier if it were simply you and her, with your husband possibly waiting in the car nearby to pick you up.
Tell her that you're not comfortable with some of the situations you've endured due to her involvement in your life, and that you'd like the relationship (I would not call it a friendship) to end. Ask her not to call, write, or otherwise bother you. Be polite, but very firm.
For example: Hey, I'm glad you could make it. I've got something difficult to say, so I'm just going to cut to the chase: I'd like to end our relationship. The fact is that being around you has caused both [husband] and myself to be involved in some situations we want no part of. I hope you understand.
Then walk away. You can then unfriend/block her, and cease to reply to any future messages. If you run into her in public, you can simply ignore her, as she will likely ignore you. Such is life.
What I like about this approach is that there's no ambiguity, and, much like ripping off a band-aid, once the initial pain of that interaction passes, you're probably done. However, not everyone is comfortable going through that. Hence ...
The Indirect Approach
Don't contact this person anymore. Don't invite her places, and don't include her in events. When she asks to meet (her place, or for a night out), say you're busy. If she asks for a ride, politely refuse (don't elaborate). Block her on social media such that she never sees you online.
She will either get the message that she's no longer welcomed, or perhaps force a conversation much like the one above.
In time, when she's stopped trying to get in touch with you, you can simply delete her from your contact lists, or block her altogether.
This approach has the advantage of potentially avoiding a difficult conversation (at least in the short term). The down-side, however, is that this is not guaranteed in the long term, and may lead to various embarrassing situations where she's inviting you places, and you're stuck making excuses as to why you can't attend. If you're certain you want nothing more to do with her, I would go with the first approach.