Kazzy, it's hard, but it's best to try to do some 'normal' stuff for yourself as well as the caring. If I didn't have my little 'distractions' then I think I would have gone mad!
I've been caring for mum at home for just over a year and a half now. Mum's onset was quite sudden, probably following a stroke which I didn't witness, so I went from having a near 100% perfectly well mother (89 at the time) to someone with pretty severe cognitive impairment within about 3 days (now 91 and physically still going strong!). Fortunately, during mum's last hospitalisation, the staff insisted she could not return home without a care package, so we started off with carers straight away. My job had to go as it wasn't possible for me to go out to work. I literally could not leave the house as could not take mum anywhere due to her condition at the time, so could not do anything at all. One and a half years on, mum still will not 'settle' with the carer (same one we've had since the start!), but there's no option for there being no carer visits as I would not be able to leave the house again (no family or close friends close by).
Fortunately, mum has settled a bit in that I can at least take her food shopping with me. The carer covers any appointments I need to go to, or the odd lunch with a friend or a full day out walking with a local group (God, how I miss my walking!). I was lucky in that my replacement at work didn't work out, so the boss offered me my old job back, albeit on much reduced hours. Sometimes I think that job is the key thing that has helped keep me sane - I was ecstatic when I got that call!
Sorry, that was all about me, but I was just trying to show how I've managed to make the best of what for me was a horrendous change in my life (and mum's of course, though she is blessedly unaware). You must have breaks, go to a carer support group to let off steam and share experiences with others, meet someone for a coffee or lunch, or just go out for a walk or a look around the shops. I felt I had to preserve my sanity in some way, and so I cling on to these breaks for me, they are my lifeline to keeping myself well.
Also, just recently, I've started seeing a counsellor. I've only seen her twice so far, but it's yet another 'lifeline' for me - just knowing that I have one more person to go and talk/offload to helps me tremendously.