While marriage might be between two people, many other people can influence it. For example, parents, siblings, and even distant relatives can positively and negatively affect your marriage. Your family may lead you down the right path 99% of the time because they care about you. But biased people and biased advice can lead you to make poor decisions. This is especially true if you’re having troubles in your marriage.
If you’ve determined that you can set enough STOPs and COREs that it’s safe to return to your relationship, you will have to stand firm against your family. You’ll get pushback from them, but set your parameters and expectations and stick to them. Demonstrate the changes that you make to everyone involved. The families involved are more likely to accept and support the marriage when they believe it's a healthy marriage for both people.