pet and dog lovers only. my cairn/silky terrier is 8 years old. he has epilepsy for 4 years

Need advice...pet and dog lovers only. my cairn/silky terrier is 8 years old. he has epilepsy for 4 years, he?

was recently diagnosed w/diabetes, then cataracts and now lipids in his eyes, which prevent him from getting catarct surgery. he is on a special diet of real chicken and rice only. he gets pills 2x daly n liquids 1x daly for the epilepsy. i have to inject him 2x daly with insulin. he's on 3 different eye drops 2-3 each, daly. to add to this, my husband has a 14yr old beagle who is very territorial. (when my dog wanders around aimlessly b/c he can't see, he bumps into the beagle and the beagle attacks. up until the diabetes n blindness we were managing and my dog didn't seem so bad off. but now, i wonder if he's suffering. he's bumping into walls & banging into things. it's so painful to see. i can imagine how it's hurting him. i love him sooooo much. i also have a new baby in the house which also requires my time. plus, the financial aspect is draining us. do u think he's suffering? am i being selfish to keep him alive? serious replies only. we don't know what to do.

Update: the think is...he is sooo young to me...only 8 and i feel like he still has so many years left. but not years like the last months he's been living. if he can't have the cataract surgery i feel he will continue to suffer and it will torture him and us. but if he can have the surgery, i feel there is hope and a light at the end of the tunnel. i can't bear to make a choice. i am so sad, crying and feel so hopeless. thank u for ur thoughts and prayers.

Update 2: plus, he is getting skinny, and he's ravenous even right after i feed him. looking at him, so weak and frail, yet once so peppy and alive is killing me.

at this point i would say that the dog is probably suffering and that it would be best for him to let him go. i firmly believe that dogs feel in the same way that humans do, and i know that any human dealing with all of those problems would most likely want to end their suffering too. just be good to him, give him a lot of attention and love and make sure you let him know what a great addition he has been to your family and how much he has been there for you. even though he may not understand he will feel the emotion in your voice. tell him that he's a good dog, pet him, and make sure you hold him while he passes over. 

i have to say, this is the first yahoo post that has ever made me cry. i will say a prayer for you and your family...........