I think you need to ask yourself which one is more important to you, these clients and whatever comes with retaining them (the money the sense of success, the referrals they bring) or is it the time with your family? Whatever your answer is, you choose that and go with it.
If you decide not to see these clients on the weekend, explain that things have changed and you can no longer accommodate weekend appointments. You don't have to explain that you'd rather have time with your family. That will allow them to make their own decision about whether that's important enough. They will respond with things like "Well, one hour away from them won't kill them." or things like that. You can just say "Circumstances have changed and I can no longer work weekends." They don't know if your husband now works weekends, leaving you with no childcare. Or if you mother is very ill and the nursing staff has the weekend off. It is none of their business.
You do have to be prepared and willing to let go of these clients and let them find someone else if the other options you have for them do not work for them.
I really don't like working Friday nights, but I made an exception for a client, not realizing that when he made an appointment, he would always want a Friday evening. He only comes once a month, thank goodness so I make the exception just for that once a month. If other people ask me for a Friday evening appointment, I tell them that I don't have Friday evening hours. If one of my regulars had an emergency of some sort, I would make an exception.
I think too many of us don't really give our boundaries a lot of thought before we start taking clients. I think we also are anxious to get appointments on the books, so we will make some exceptions in the beginning. It is very hard to get out of some of the patterns we establish that way though. I still do it myself. But, what I do now is when i find that something I thought would be just "one exception" starts becoming a pattern that I am not comfortable with, I decide on some options for the client that I am comfortable with and I offer those to the client. If it doesn't work for the client, then it's time for them to find another therapist. I want my practice to fit my needs and my lifestyle. I don't want to feel "ruled" by it and by my clients. I am the boss and I get to set the rules. If I feel like the clients are ruling and taking over, then I will begin to become unhappy in my work. When a client leaves me to see another therapist, then I realize that for one thing, the client is going to be more happy and also that will leave the room and energy in my practice for the type of client that I do want to attract.