Was it rude of me to write to my friend to tell her i'm not attending her wedding?

A girl i know (used to live in her city two years ago) asked me unexpectdly out verbally would i attend her wedding as a guest. As she asked me over the phone and i wasnt prepared would i attend her wedding pre invite i said yes there and then as i got embarressed into it. Then she sent me the wedding invitation. Now one month before her wedding, things have gone wrong in my life. My partner lost his job, my mom is sick in a mental hospital, i've money worries and am stressed over a health matter, and i'm in therapy over another matter. I didnt have the energy to phone the girl and explain all this and didnt want to. I rather leave my problems for therapy and i feel this girl is too nosey anyhow. Also i find the relationship a bit pressursing, she is too demanding of my time and was ringing and texting all the time and being nosey about my problems that i shared wtih her once upon a time and which i dont wish to discuss with her each time. I couldnt face a telpehone call to her so I emailed a nice email wishing her and her fiance the best of luck and saying i was sorry i had to pull out and outliend my problems briefly explaining that when i accepted her invitation a number of weeks back things were different. I then invited her to my city for dinner and hotel for one night and said me and my husband would meet them after the wedding and that would be my present. She then emailed me and said she didnt wnat my present seeing as i had financial worriies and said that she was real dissapointed i didnt phone instead of mailing her. Now she hasnt contacted me since to even ask about my mum. Whos unreasonable? I wish the girl the best, i dont want to fall out with her, but its preying on my mind. HOw should i move forward.