The first thing to address is what Cid mentioned above - the main danger of posting things like this online is giving away your identity, particularly in relation to something you're feeling vulnerable about. You don't need to fear that from Spam members - most of us vent here at some point and support is always there - but this is, after all, a public forum that anybody can view. I'm very free with my details on here, however, and no harm has come yet, but it is simply something to keep in mind.
But to address the issue at hand:
About your mother... how you deal with this is very dependent on your view on parenting. See, you can either believe that parents are parents first and people in their own right later, or the other way around. Neither is right or wrong, but the best way to deal with any situation obviously depends very much on you as an individual. If you feel the first, then unfortunately, your mother has not been there for you and has let you down, and maybe you were right to cut your ties and not let her drag you down with her. As much as that hurts, this is like cutting away a necrotic limb - it hurts like fuck and it may feel like something is missing, but it will save your life and make you happier in the long run, without poisoning other areas of your life. If you feel the second... well, that's a hell of a lot harder, because in that case a parent is as much a friend as anything else - and you have to support them through the rough times as much as the other way around, even if that means embarrassment and pain for yourself. And if you're that sort of person instead, cutting them off and leaving them to their own devices may well breed regret later.
About friends... as hard as it is, the best advice I can give is to attempt to separate your inner vulnerable emotions from what your friends joke about. Your hurt and upset is 100% understandable and reasonable, but your friends' comments are not meant to target those - they just see a funny story about their mate, the same way everyone takes the mick out of their friends for stuff. You have to try to take their comments in that light.
To try to think of an example - I generally look super scruffy and dishevelled and shit, and my two best male friends are very image-conscious and very much believe in looking smart and presentable. They take the piss out of how I look all the time as a running joke - but it's actually been a source of real insecurity for me in the past, and they even know I used to purge (make myself sick) and starve myself because I got so worked up about it. I take their jokes as the lighthearted fare they're intended to be, and try not to think of them as real criticisms that might hit my confidence too badly; to not take the comments personally, or seriously. They make the joke because it's there to be made and we all take the piss out of eachother, not because of their actual thoughts and feelings about me.
I know your current problem is a very fresh wound and is somewhat more serious and complex, but I hope that illustrates my point - perhaps the word to use is "compartmentalising".
Talking big-picture though, it doesn't sound like you much fit in with your friendship group. You're a person of empathy, whereas they don't give a shit about others. That may be an issue of maturity - I had similar issues with the friends mentioned above for years, but eventually they matured and now they're two of the best friends I could ask for - but if not, maybe it is time the insensitive asshats are relegated to being friendly acquaintances and you seek out likeminded people who will empathise with and support you the same way you would for them. I understand feeling socially inept and not knowing where to start, but... in general, settling for unhappiness because it's comfortably familiar is one way to guarantee a miserable life. Major events like this can be epiphany moments that make you realise you need to change something; maybe, right now, what you need to change is your main friendship group, so that in future you have folk to support you through stuff like this rather than feeling alone and vulnerable. I mean, true, we're all here for you - but we can't give you a hug, unfortunately.
And that's enough advice instead of sympathy. I can't pretend I have the experience to empathise, but I utterly sympathise with how you're feeling and I am sorry that you're suffering through this shit. It's not something that anyone should go through, feeling that neither parent nor friends are there to support them - but I think that Idle is right in multiple regards in this thread, in particular that over time your friend group will hopefully morph and change in positive ways, and I hope you can take comfort from her similar experiences.
