We understand entirely
Hello Rosie
welcome to the forum! I hope you find that talking to others will help you.
Early Onset always seems harder for the people who have it, or who look after people who have it, but in truth, the whole area of dementia is hard for anyone who is involved. Each age group has different, but no less challenging, problems.
You say "I am looked upon by the family as the strong one but this isn't so". I think you most likely are strong, but dementia in a loved one dents one's confidence massively, mostly because there is so little one can do to help, and nothing to cure it. All you can do is your best.
Feeling guilty at leaving her.... Yes, of course - we all do when we leave them after a visit. Guilty too when we enjoy ourselves elsewhere and in our mind's eye, see them back at the home or hospital, unable to enjoy themselves. Guilty when we see what they are eating [though it may be very good] and want them to have food we have prepared. There's a lot of guilt, though in reality it is self imposed, and again mostly powered by our frustration at being able to do so little.
What can you do?
Look on the positive side and build on that. You are visiting her. Many people don't visit their relatives. She WILL know you are there and that you care.
Keep visiting, and talking to her. Treat her as if she is the same as she was SIX years ago. It will be hard because there may be no response, but I am convinced that it gets through to them. They know that you care enough to do that.
Don't beat yourself up about the situation. There's just so much you can do. Once you have done that, keep your life outside as normal as you can. Not only for your own benefit, but so you are well enough to be able to visit the next time, and the next.
Use the forum to rant and rave a bit. It does help to dump all this stuff out. It also helps others to see someone in the same situation as themselves. It is a lonely thing, being a prime carer.
Whereabouts in Wales do you live?
Regards