Was he rude or am i being too sensitive?

[Jinglebells10]

I work in an open plan office. I work with a guy who is almost 10 years younger than me. We usually get on fine. I have been there and listened to him when he's struggled with MH. He was in a really bad state at work the other week and i listened and gave advice and was really concerned for him. Today i sat opposite him. He then sends me an email saying god you're so short. I replied well that's random, i like being short. Then me, him and some other guys where talking about food as someone had brought things in for a birthday. I said i wanted another treat and in front of people he starts mocking me. Saying i'll have to roll you down the hill and that i'm the cake monster. I try laugh it off but didnt know what to say as the other guys were laughing. I just went quiet and left them to be immature. About 15 mins later he stood up as he was leaving and said really loud, almost a shout like cya fatty. I'm in no way over weight, just stated i wanted another cake. For some reason i felt he was trying to put me down in front of others.
The other week i was helping him with his work, he asked what i was doing for halloween. I said nothing but i was excited as i dressed my son as a skeleton for nursery. I'm not 100% sure what he said but it sounded like he said my son was a freak. I said to him excuse me and he said i didnt say anything.
AIBU to be angry at him. I stand by and listen to his MH issues and then he talks to me like this? I don't understand what his issue is?

Good message but I'd remove 'don't want to make a scene'. You wouldn't have, he did.

hope that message does the trick!

He fancies you OP. Acting like an 8 year old pulling your pigtails in the playground.

He's negging you.

Don't accept it and pull him up when he does it, or take it to the manager.

Start to distance yourself, there may be a chance that he's using his MH to have an excuse to have one on one time with you and all of your attention.

He replied saying I didn't know I upset you, sorry. Then came into work and sat beside me! Was quite awkward. We hotdesk so he had a number of other desks to choose from

Text was phrased OK. But generally it's better not to get into texting especially if a work colleague is being abusive. It just creates a 'secret' communication channel and it's not suitable for a work situation.
He has to be called on his behaviour to you, every time.
He's an adult not a child. Do not forget that. Adults are responsible for their own behaviour. You are not his mother or his big sister.
If you are concerned about his mental health, tell his manager. Similarly if he is insulting you take the same approach. Hold your boundary and do not blur the lines between friend and work colleague in this situation.

@seaweed42 if I need to go further if he doesn't stop I can still use it as evidence. My feeling is he will stop in the short term but will carry on at some point down the line.

Hmm i dont know if he fancies me. He did once try it on with me a year ago and i said no sorry you're too young for me. But we have been ok since then. He's done this once before and i avoided him, he asked if he had done something wrong. I just said i'd been busy. Now hes back to being an idiot again.

He is looking to control you.

Maybe he liked getting a lot of attention when you were being helpful about his MH issues.
Then he tries it on with you (bleugh!).
As with most immature men, if you turn down their sexual advance, they need to punish you - hence the cake/fatty remarks.
Now he is making unfounded, nonsensical comments about your son.

& yet you say he does now harrass the other 2 managers like this?
You need to establish boundaries right now.

As per pp above - call him out every time he is rude, disrespectful or imappropriate. You may find this hard at first, but it is actually simple - "You are being rude/disrespectful/inappropriate. Stop it now"
& if he does not stop, or repeats the behaviour:
"I have warned you before about your rude/dispespecful/inappropriate remarks. If I hear one more from you, I will be taking action & you will be given a formal warning."

He is testing you.
Pull him up short OP.

I was thinking of maybe sending him a message along the lines of "i don't appreciate you making fun of me how you did today, i'm all for a joke but not at someone else's expense"?

DO NOT DO THIS.

You will be opening yourself up to endless justifications/accusations/minimisation. You need to shut this down, not open it up!

Keep your powder dry.
Wait until his next inappropriate remark, pull him up on it, & tell him next time, you are reporting, escalating, giving verbal warning - whatever. Just make sure you see it through.

I'd pull him up on this every time

Him - cya fatty
You - I've asked you once already not t one so rude

Him - I'd roll you down the hill
You - rinse repeat

I'd look at him in the eye and not smile or laugh when I said it, even if it creates a silence. Just let him stew in his own juices.

Although he's told me he refuses counselling and medication so he isn't helping himself.

Right.
And this is the same manchild who you have been there and listened to him when he's struggled with MH. He was in a really bad state at work the other week and i listened and gave advice and was really concerned for him.

It doesn't suit him to get professional MH help.
It suits him to have you dancing to his tune when he wants your attention.

Please be very clear to yourself about this - YOU ARE NOT RESPONSIBLE FOR HIS MH. He is just a co-worker, & he is a rude & immature one that you do not need to pander to.

@messolini9 no he doesn't behave like this with the 2 managers.

Yea he came in and was crying asked to speak to me and we had a chat in private room. He said he felt like he wanted to kill himself but didn't have the guts to. Although he said something strange and said it's not the reason you think it is?? I don't know what he meant by that as I didn't have a reason to think something triggered him. He said I could let the manager know as he couldn't stay in work in the state he was in.

My manager did say to me just remember don't burden yourself as it's not down to you to worry about him, you've done all you can. Because I was worried I had not heard back from him.

When he came in this morning he said to me "don't worry I'm not staying". I replied I'm not worried. Really don't know why he decided to come sit beside me, was this a form of intimidation? To make me uncomfortable?

Yes. I think so. As others have said, he like the attention from you it is not prepared to take responsibility for his own health issues.

You think he was trying to intimidate me?

It is important for you to understand that he made a scene at your expense and involved all your co workers in it.

Coming in and sitting next to you was yet another instance of plausibly deniable harassment.
He has likely been passive aggressive harassing you since you told him no and it is getting worse, it will only get worse. It always does.

Some people are just so bleeding peculiar there is no fathoming them.

Brilliant :( I've already had a sexual harassment case at work a few years ago. He still works there but did get disciplined. Really hoping this doesn't turn into harassment as well