Yes, it can be possible to have a good life when you have MS. He has the "best" kind there is, with intervals (we hope long ones) between attacks and not a consistent deterioration. I used to be a volunteer at a Multiple Sclerosis Therapy Centre, and there were a lot of people attending who had been diagnosed years ago and were still relatively OK.
The husband of a very good friend has MS, the gradually worsening type,. He was diagnosed way back in 1980 or so, and continued to work for many years. He is now confined to a wheelchair, and has carers coming in to help him get up and dressed and to go to bed, but he is still at home.
For support outside the immediate medical teram, look for your nearest MS Therapy Centre at www.msntc.org.uk/ and phone them. They are happy to talk to relatives and reassure them, and tell them what facilities are available at that Centre. specialised physiotherapy is one very useful service.
The Centres have no formal connection with the MS Society. They were set up in the 1980s by a neurologist in Dundee, at a time when very little was known about MS. He was an enthusiast for oxygen treatment, so most of the Centres provide that, but they also do physiotherapy, informative talks and alternative therapies like acupuncture and so on - but their chief value is in meeting other people having the same experiences, and swapping stories about what is helping symptoms.