Resist the temptation to go to your default reaction which is to cut people off. That's one of the reasons you are in therapy; this IS the work. Get the appointment scheduled and get back in to see her at that appointment to to continue the work you were doing. You can tell her then how you reacted to her being gone. That's where you talk this through. It will be okay. She didn't abandon you, even though it feels that way. She simply went to be with her daughter at the birth of her grandchild. That decision wasn't about abandoning or betraying you. You need to discover that you can get through this and that people don't disappear from your life simply because they have other things going on in their life. The only reason she would disappear from your life right now is because you decide to make her disappear by running. Do differently this time. You can do it, and you can grow in the process.