Your DS is so little I think this can only be achieved over a long period of time. No quick fix I'm afraid but steady acclimatisation, I appreciate you were poorly and OH meant well but from DS's point of view, this man was taking Mummy's place - I don't want you I want her! Probably better to do simple stuff together, let DS get used to him being around. It's a bonus that your OH's DDs do get along with you, neither you nor OH are immune to the children affecting your relationship - as many on this board know it's not always a picnic.
As the ^^ wise posters have said, it could as easily be about your little one's age and clinginess not an aversion to OH. I hope as an adult he didn't take it personally and is sensible enough to realise from DS's perspective, anything new is suspicious and he doesn't know what is a temporary arrangement or something permanent - he's too little to weigh things up he just knows what he likes NOW. He can't verbalise it yet but he can certainly show his displeasure.
What do you mean 'your OH gets upset and can't handle it' when your ds has a tantrum? At 11 mo they don't really have tantrums as such - just get upset? Does he (OH) get angry, or take it personally, or do you just mean he can't comfort your ds the way you can?
My DD was just like that at that age - and she hadn't had an abusive dad or anything, though I was a lone parent, and she was clingy. She would be absolutely fine with other people if I wasn't there, but if I was would have hysterics if I wasn't looking after her. Was almost as if she felt I was neglecting her or something if I was in sight but not the one feeding her/pushing her pushchair/etc. Best thing is probably to let you OH have little bits of time with DS when you're not around at all, but accept that he wants you to look after him when you are around. It will get easier - your DS will get used to OH, and a year from now will probably be completely different about being left with strangers anyway.
DS is 11 months old and has had me to himself for 3 months while we were living in a refuge, now Ive met someone and he stays over a few nights a week.
Last week I was very ill and tired so he said he would help out more with DS. Everything was fine until DS heard my voice, at which point he threw a massive tantrum and refused to take his breakfast from my OH.
This has continued to be the case and I have even asked my OH to come over more often so DS can get used to him being around.
Is there a way for me to help the pair of them bond a bit better as when ever DS has a tantru my OH cant handle it and gets very upset. He has 2 kids of his own ages 2 and 4 who get on with me really well.
Ive tried to explain that it probably has something to do with DS having an abusive dad (which is why we were escorted to a refuge!) and having just me for such a long time.
If I am not around DS is fine, he only seems to kick off while im around or if he see's me leave the room.