I'm very sorry that you feel that way, just like [MENTION=10438]JCoatsworth[/MENTION], I can't say I really understand though. It's one thing to hate s7, but even then it's not the end of the series, maybe you should give the comics a try (although I feel like you'd hate them even more if you disliked s7). And also, there's actually a good amount of people that dislike Buffy, so you're not the only one in that aspect.
One thing I don't understand is how you find that Buffy treat Spike badly in s7. After the events of s6, I think she treats him the best, not only that she ever has, but the best that she could which regards to their past. For the first time they are friends, I love their relationship in s7.
S7 isn't perfect, I'll give you that, I'm also fine with people saying it's the worst season or that it's shit (even if I disagree), but the idea of it ruining the entire series if new to me (literally, first time I hear it), so please bare with me, I'm not trying to insult you or change your mind, I'm just trying to understand.
The way I see it, if it gave you 4 awesome months, then it's worth to keep as a positive memory, even if you never revisit it. It's like going out with someone and having a rough break up, I don't think it diminishes the positive experiences you lived with the person. And also, think on the bright side, you got to meet an awesome community on this board 🙂 One of the reason I love the series so much is that I got to meet so many awesome people and make new friends. I guess what I'm trying to say is to look at the positive, not the negative.