Simon-
Sorry to hear things are going so rough for you now. Sounds like your Dad is having some problems of his own, which is, still, no excuse. Keep building yourself up. If you can't get support from where you'd like it, try and find it somewhere else - though, I know that takes energy and effort you might not feel like you have right now.

If you can't find a teacher or friend to support you in your area (music?) - try finding a "virtual" guru. Read a motivating book like "Free Play" by Nachmanovich (about creativity in music) or "The Artists Way" by Cameron (about building up confidence in your inner artist/musician/writer). You said you weren't giving up. Good for you! Books like these can really help keep you motivated when your family is raining on your parade. If you can't find a teacher, mentor, or therapist to support you (cost prohibitive?) you can at least get a book from the library.

As far as your support system, well I learned long ago that, as hard as it is, you might have to step aside from the one you were given and create a new one for yourself.

It doesn't sound like anything you do is going to make your Dad happy, so maybe start focusing on making you happy instead.

Keep breathing in and out and try to keep that spark of imagination and inspiration alive. Like you said, you "have to keep plodding along" only, once in while, skip just for the hell of it - even if you don't really want to.

Thinking positive thoughts for you....