It's true that there isn't really a Gnostic version of the Ten Commandments, and I certainly don't think we ought to have one; firstly, I don't consider the Decalogue to have much to do with living a moral life, and the moral customs and practices of an ancient largely nomadic culture do not serve us well in the 21st Century.
In the Gospel of Thomas, The Living Jesus offers relatively few directions on how one should live or how once should practice. The first logia where we encounter Jesus giving moral advice is the sixth, and the Greek fragment is usually translated like this:
His disciples asked him, "How should we pray? Are we to give charitable donations? What food laws should we follow?
Jesus said, "Do not lie, and do not do what you hate, because the Truth makes everything clear. There is nothing hidden which will not be made clear."
So, the first injunction to live a moral life is very simple: don't be a hypocrite and don't lie. That's a very difficult thing for many of us, myself included, to accomplish. We often see people behaving poorly, and we say or think about their behaviour in a negative light. Of course when we then go on and do there very same thing ourselves, we often give ourselves a pass on our behaviour when we just passed judgement on another person!
This same theme is continued in logion 14 where Jesus says:
If you fast you will cause harm to yourselves. If you pray you will be condemned. If you give charitable donations, you will cause harm to your lives. When you go in to any land and walk around in the districts, if they receive you, eat what they give you and heal the sick among them. What goes into your mouth will not pollute you - it is what comes out of your mouth that will pollute you.
Here, it is usually understood that Jesus was referring to public prayer and bragging about giving alms. Instead of bragging about the depth of our practice or about how much or how often we give to charity, we should simply do these things quietly without drawing attention to the fact that we do them. It's a normal desire to be recognized for one's good deeds; we, as people, enjoy being esteemed by our peers. Be careful, because you can become attached to the praise you receive from others; what happens when you cannot give anymore? Do you become depressed or spiteful? Envious of the praise other receive?
Also, don't worry so much about whether you should or shouldn't eat food; if it's given to you, eat it and be thankful. You're more likely to cause harm to yourself and to others by what you say than by what you eat. It's easy to stop paying attention to your thoughts and emotions and say something that is inappropriate in the current situation, or to say something which causes harm to someone else.
In logion 25 we have The Living Jesus exhorting us to "Love your brother [sister/fellow humans] [the Greek word carries a gender-neutral connotation] like your soul, guard him like the pupil of your eye."
Have you ever had something in your eye or perhaps scratched part of it? It's very painful, and protecting your eye is a very instinctive thing. The Living Jesus says that we should love our fellow man (and woman) as dearly as we love ourselves and that we should be quick to protect them from harm.
There are not many direct moral exhortations in The Gospel of Thomas: love each other as yourselves, don't be a hypocrite, and watch what you say.
I think those things are difficult enough without having to add anything else to the list; I certainly struggle to live up to those ideals each day.
I cannot, and will not, tell you who to love, or how to love. I will not condemn your relationship because it defies convention. I will try to be mindful of how the things I say affect those I say them to, and I will try to avoid behaving like a hypocrite.
That is all I can do, and that is all I can ask anyone else to do. If we can all do those things, then the Kingdom of Heaven would indeed be manifest on Earth.