My best advice huh is reply be polite but say your very busy and you have lots going on in ur life right now but say it was nice to hear from her. That way you won't come across a xxx

I don't think I can help you out with that kind of problem, because there is (that's just purely my opinion) no really "right" option or decision, it totally depends on the persons and the situation. I used to be in a similar situation with a girl, who used to be my best friend like, one year ago. I don't really know how it happened, but we draw appart more and more as time went by (even though we were extremely close), and finally, we abruptly stopped texting and talking to each other. I felt terribly guilty at first, because I thought this was my fault if we weren't talking anymore, if we grew so separated and so on... Idk why, but I was convinced it was on me to rearrange the situation, to go and talk to her, but the thing is I realized I wasn't sure if I wanted to. She also never tried to contact me, so a part of me was thinking "Why should I be the one trying to fix things ?" . She seemed totally fine without me, and I was kind of mad for it, so I didn't try anything for a few months. But after a (long) moment, I came to wonder why we were in this situation. We used to be like sisters, so why such an upturn, without any visible reason (this is where it is different from your story, because if your friend is hanging with people who are badmouthing about you, the way of seeing things and how to react must and should be different.) ? This is when I decided to try and contact her, thinking that "maybe we could sort things out, just explain about this and maybe be friend again ?" but this was in fact useless. I think she moved on too, because she made it clear that she wasn't near to talk to me ever again. I think that those few months without any contact with each other completely drew us appart, made us almost like different persons that weren't even close. She didn't even want to try. She was just so cold with me, that I thought it was like we've never been friend at all. I was then kind of sad, because, wasn't that such a waste...

The agony of being a human . Anyway just follow your heart. Dont feel guilty .Its not like she treat u nicely and all. People come and go.

Dude I feel you so hard. I wish I could give you advice.

When you don't want to spend time with her, chat with her... don't. You have no reason to feel guilty. People change.
If she writes you, you don't have to reply. If she adds another message under the first one asking "Why aren't you replying?" answer after few days with "Sorry, I'm busy with life. Sorry." It will maybe repeat 2 or 3 times but eventually, she will give up. You don't have to feel guilty because of this. Seriously.
I know it may sounds harsh and I may sound like a (because this is what I do, because I'd feel 100x guiltier if I just told them "Hey buddy, sorry but I don't wanna spend time with you, we have different views on things and you also only contact me when you need someone to lean on") but if she's only using you, then what does she deserve?
Or maybe, if you want to change things and maybe meet her in private without her friends, ask her to grab coffee with you. Then you will decide if she's really the person you have no intention to spend time with. Hope you'll figure it out! But no, you're not a bad person, you are just a human. We all are.

I'd decide whether or not I want to keep this friend. If I didn't, I'd never reply.
If I did, I'd think about what change I want in our friendship and think about ways to get that across effectively to this person based on what I know works with her.
I'd think about what I want first. What do I want her to do? Say it's I want her to take up for me when her friends make fun of me. Or I want her to call me for more than just favors. I'd say those things to her. Flat out, but nicely.
I'd say "Though that's sweet of you to say and I appreciate hearing it, I don't know if I can say the same since it felt to me like we had grown apart. We used to have really good times together but now you're friends with people who make me feel bad. Not trying to pick your friends or anything but if I'm a friend to you, too, I'd like it if you stood up for me in those times."
BAM. I'd just put that out there. And if she refuses to make any changes to save your friendship then she doesn't miss you. She just misses having you there for her. There are a lot of selfish people in the world who are like that. When you're by their side you're nobody. When you're gone and not there to support them, THEN they miss you. If she's a friend like that, you don't really need her

I swear man, me and you could sit at a cafe and talk about like this all day long. I know exactly how you feel cuz I went through same too. Sometimes I just fake it and say I miss them too since I don't want to hurt their feelings but sometimes I just go 'well, I don't miss you'. I made it sound like a joke but in reality, I actually meant it.

I know u wanna avoid her but still reply her back. Just keep it blunt and simple so that she get the message that u don't wanna talk to her. If I were her, I rather see a replied back than seeing nothing at all.

Anway, that is just what I do when I'm in this kinda situation. Don't think about to much hun. like this happen all the times and trust me, it a pain in the since it makes you feel like . Hope things goes well :) fighting hun :)