I feel exactly like this so I absolutely understand. My T's life hasn't been easy for a long while so I feel bad for feeling it, but in the last year she's got and done everything I truly wish for and can't due to chronic illness, being single, how my life has turned out.

I've never been able to talk to her about it as she has so much empathy and I think she'd feel terrible if I told her this. Like you, I am happy for her, but also very sad for me and how things have been.

I don't know what the answer is apart from to try and focus on myself and what I have and can do with my life. Unfortunately due to health and other limitations there isn't much but I try to be grateful for what I have. I know that doesn't help though - it doesn't help me much.