Dear Sarah,
I've just got a message from your brother and I was sorry to hear you're in hospital. Hope this is nothing serious and we can go to the seaside next month like we planned. Get well soon!
Love, Krzysiek
I was sorry to hear - przykro mi było, gdy dowiedziałem się, że
to go to the seaside - pojechać nad morze
like we planned - tak, jak planowaliśmy
get well soon - wracaj szybko do zdrowia