Letter.

Hi! Chris, I am so glad too for your letter and thank you for your invitatiton to spend the next weekend with you. You make can be sure I will go/come there.
In your letter you told me there will be a Festival of Science and the programme , in your words was sounds great, and I would have to choose between two activities, so I let me tell you, I would prefer to go the performance called 'Can animals speak'? I have always been interested in that sort of thing, plus I love the animals.
I would like you to send me the programme for Festival of Science, please!  I would love to see it, so if we felt like we wanted to go to other shows we could.
Finally, I' m sorry, but I couldn't stay with you for a bit longer, but as you know , my mother has Alzheimer's ,and I have to visit her. Anyway, this weekend will be fun.

See you
Best wishes.

Hi! Chris,

      I am so glad too for your letter and thank you for you r invitation to spend the next weekend with you. You made sure I will go there.

 In your letter you told me there will be a Festival Science and the program me . Your words were great  and would have to chosen

between the  two activities. o I Let me tell you, I would prefer to go the performance called ''Can animals speak?" I have always been

interested in those  sort of thing, plus I love the animals.  I would like  for you to  send me the program please . I would love to see it. If we felt like to go to other show.
Finally, I' m sorry, but I couldn't stay with you for any longer, as you know , my mother has Alzheimer's ,and I have to visit her.

Anyway ,this weekend will be fun.See you soon!

Best wishes,

(YOUR NAME)

Letter.

Hi, Chris! I am so glad too for your letter and thank you for your invitation to spend the next weekend with you. I am sure to go(if this is your meaning?).
In your letter you told me there will be a Science Festival Science in the programme. You words were great, and you said I would have to choose between two activities. So I let me tell you, I would prefer to go to the performance called 'Can animals speak?' because I have always been interested in that sort of thing, plus I love animals.
I would like you to send me the programme for the Science Festival Science, please. I l would love to see it and if we felt like it, to go to other show, too.
Finally, I' m sorry, but I couldn't stay with you for a bit longer but as you know, my mother has alzheimer's, and I have to visit her. Anyway, this weekend will be fun.

See you
Best wishes.

Very well written! The conjunctions can be improved.