Hi Marshmallow,
Working with our family members is one of the toughest aspects of bringing a meditation practice to life. It is wonderful that you are noticing the struggle and wanting to work with it.
I would start with lovingkindness towards yourself. Let yourself feel the pain of feeling unseen and unloved by your parents, and notice what arises in talk, image and feel. Then, give yourself the love and compassion your wish your parents and family had given you. Meditation can be a wonderful way to re-parent ourselves. As you allow yourself to feel the pain of your childhood as it arises in the present moment, and observe it without judgment, you will begin to purify the past and find more space and freedom.
During this process, you may want to limit the time you spend with family if it is too painful. This can be another way to take care of yourself and develop healthy boundaries. You don't need to explain what you are doing to them as that will lead to lots of drama, just be aware of whether you feel resentment when agreeing to do something with them, and if so give yourself permission to say no. They may be upset and may try to guilt you, but you are taking care of you and there is nothing wrong with that.
Over time, you may find that some of the patterns that you see in your parents and family are also within you. You will see the pain that has caused these habits and patterns, and recognize the need to forgive yourself, and them, as this is really the only way out of suffering. Don't rush the forgiveness of them part, though, it will happen on its own time. Continue working on forgiving yourself and loving yourself.
For me, I have learned to accept my mother, for the most part, despite her having been cruel and critical for my whole childhood. I find the more I am able to accept her as she is, the more I see that she is truly trying her best and suffers so deeply. Lately I have been really enjoying spending time with her and loving her, which is truly a miracle. I have a brother who is frankly an a**hole, and while in theory I can accept him as I know he's trying his best, I choose to spend very little time with him as he is such a negative and aggressive presence. I send him lovingkindness from a distance :-)
Over time, mindfulness practice (and therapy if you are interested in exploring that modality) can help you come to peace with your family of origin. You can thank them for having brought you up, relate with them in healthy ways that protect your boundaries, and then choose to surround yourself with a new Sangha or supportive community that you feel is nourishing and supportive.
Lots of love,
Paula