stepson wont sleep alone?

so my stepson is 2 and a half years old. he stays with us anywhere from 10-14 days a month. and this has been going on for the past year. but this last time hes come over he refuses to sleep in his bed. he started screaming for me at about 10. i went and held him, tried to lay in bed with him to calm him down. as soon as i got up he would start screaming and try to grab me. my husband tried to put him back to bed. he started screaming at the top of his lungs and kicking his legs and arms against his bed. i caved and we brought him into our bed to sleep but it was awful lol. i was getting smacked in the face and my husband was getting kicked all night. im pregnant and finally gave up trying to sleep at about 4 am and went downstairs to watch tv. i can't do this for another 13 days. is there anything we can do to help him? he has a fish lamp for night time that the fish swim in. i dont.want to encourage this but i dont want him to throw these tantrums