Would asking my line manager to do a email to everyone in the workplace to say I have aspergers be a good idea? (Also, asking for mentor a good idea?)

I've been working there for over 5 years now, even though I know that some people know that I have aspergers, I don't know who does or who doesn't really. And the problem is that I never have been able to start a conversation with anyone myself from when I started working there until now 5 years! I've been able to reply to others when they ask me something but it mainly just involves work related stuff and not just general chatting? Also when people in the workplace ask me to do something, I always need slightly a longer time than a NT to process the information they said and to understand what they mean. I worry that if they don't realise I have aspergers then they may wonder why and not understand how to actually speak to me to pass the instructions on about what they want me to do?

Also, noone talks to me that much and I want them to understand why and not for them to just think that I just don't want to speak to them? Because I always appear socially awkward, they may just not know why etc. 

Also one thing I overheard my line manager (this was a while ago) say to one of the secretaries was that I hate everyone etc because I didn't go to the Christmas meal. I was very annoyed when he said that though he has no idea how annoying this could be especially because he should of known why I didn't go to the meal not because I hate everyone, I didn't mention anything about it though but he has been much of a better line manager now probably because he tried to understand my condition a lot more now.

But yeah overall I just want all people at work to know I have aspergers and that is what explains why I behave the way I do at work. I sometimes can be uncomfortable with telling people that I have aspergers but if there is a good reason to I don't mind at all.

Would it be good to do this then overall? Would my line manager actually help me draft up a email so he can email everyone in the workplace to make them aware that I have aspergers and how it effects me and what other additional information is good to add on as well?

I feel like this maybe a good step to take, perhaps the first step to make the workplace a slightly more relaxed environment for me because I will probably be working there for quite a long time from how things are looking.

Also I haven't got any mentor in the workplace, I feel like I need at least someone that I can feel comfortable to talk with privately about my worries concerns and progression etc my line manager is good but I don't feel comfortable talking to him unfortunately, He take things too seriously and jokes a lot which is good but then when the times he is serious, It just makes me uncomfortable and anxious when asking him things. I need someone who is serious but makes me relaxed to talk about things if that makes sense!

From when I started working there until now which has been quite a long time, I have never felt relaxed, I always felt tense and anxious and just got on with my work constantly, but now as I'm getting a bit older, I think I know that this could be one of the issues what is causing this, still not sure yet! The other thing is the amount of different assisting tasks I done, I feel like I just don't get appreciated enough. :(