Hi Lmd, well it's really good that you managed to talk to your GP about what's been going on for you. From what you say that probably wasn't easy for you, so well done!!!
As for saying things you don't mean or being hurtful, well moods can play a big part in that. And depression...............maybe linked in with that there's some apathy?? less interest or focus on things (and people!!)?? emotionally drained?? lack of concentration?? sometimes finding conversations a bit "overwhelming"??
But regardless, it's going to be hard (if not impossible!!) to focus as much on other people's needs/feelings/perceptions in conversation if you're depressed. And not always that easy being "nice" to people, even if you really want to be when you're depressed.
So NO you're not a horrible, selfish person!!! You just need a bit more help with where you're at right now, so cut yourself some slack, hey??
As for anti-depressants well sometimes they can effect people differently, the main thing though is to keep your GP up-dated on how it's going. It might be they need increasing a bit, often doctors will start at a lower dose and work up from there as needed or it might be ultimately you need them to be changed for some different one's/or need a different medication. But if that's the case then there are plenty of meds out there and and plenty that can help people get to/back to where they really want/need to be.
And for support while you're working through this...........there are some really understanding, supportive people on here so keep posting and/or looking around and.........welcome to PC!!!!
Alison