My DD is very attached to me and cries if I leave the room too. She was worse at one stage and wouldn't let anyone else hold her at all, not even her father could hold her. During that stage I just tried to expose her to people by getting out or having them come round and at some stage she seemed to grow out of it. Now she's ok with other people but she really just wants me all the time. I make my DH put her to bed every single night so that it's not just me doing it (she does cry at first but settles relatively quickly). My DH also takes her out on regular walks alone and will spend periods of time playing alone with her (sometimes I just hide out in the bedroom). If someone else visits I try and leave her alone with them for a bit too. I also tell her when I'm leaving and then announce when I return. All of that has helped us but she is still very attached to me and will still cry if I leave the room. However, she does settle fairly quickly now.

HTH