Violin sounds flat and disgusting?

So I'm recording tomorrow along with a flute and clarinet, a piece we wrote. I've only been plying it for a few days but the wound is wonderful when I hear it first hand as I'm playing it. I decided to record it using Voice Memos on my iPhone 5s but the moment I played it back, it played flat and awful. It ashamed me that I'd been playing that out loud for my entire family for 2 days straight.
It's not just the piece, anyone I try, even famous ones with great melodies, sounds great to me but is actually disgusting being recorded.
How can I improve my playing so it sounds good on recording? Or do I need a better recording device?

Clean it

It's the recording device, not you. Not just the iPhone (although it does better than some) but actually all built-in microphones on all devices (except some recording devices) are not designed in a way that they can handle music. Even your voice might sound a bit different when recorded on something like that than what you hear in real life. You need equipment that is designed for recording music. If all you need is something to play back your own performance, a USB mic for your computer is enough. If you are recording something others will hear, you need more sophisticated equipment as well as a room designed for recording. Software can also be an issue. Voice Memos is meant to record spoken voice messages, not music, and how the software interprets your input is sometimes just as important as what input the hardware is capable of collecting.

If the issue is simply having a recording, consider high-quality MIDI software.

I think it was Silver Linings Playbook in which MIDI credits appeared during the closing credits even though Danny Elfman's name also appeared in the credits. There's much I don't know about him, but I doubt that he resorted to MIDI software for the Sledge Hammer! Opening theme in '87 or so.