i'm also on a 5 week break (and now just over a week left) and on a self-imposed ban on emailing my T, which probably wasnt such a smart idea after all...
so my advice would be to email her, she said you can and she understands, she wouldnt have said it if she couldnt handle it. i think T's are good at balancing their work with their life, they have to be in their line of work. i'm sure she can think about her clients once in a while and still enjoy her holiday.
i think for me the guilt and the 'bad contamination' feelings came afterwards... after i emailed and waited a few days and didnt get a reply. i think you also need to consider, would you be ok with waiting for a reply and how long that might take. if she's away she might not have internet access very often. this is one of the reasons i didnt email this time. but getting an email can also feel so reassuring and like it is going to be ok. i found that she didnt have to say too much, i was happy that she did reply.
its hard to know, hard to predict how you will feel, how hard it will be to wait etc... but it might make you feel better to express whats on your mind though and share that with her.
dont worry about being selfish, if its something you need to do to look after yourself, i'm pretty sure she'll be glad you did it and won't think it selfish at all.
hope it goes well whatever you decide its helpful for you.
puppet