Son, 11, scared of being alone

How can I get my 11 year old, soon to be 12, do things by himself in our home?  Ever since he was born, he has never like being alone anywhere in the house.  He always has to have someone with him while he's doing something.  This has put a strain on me, due to the fact, that I am the one he preferably wants to be with him.  This causes problems.  I can't get anything done, or I can't be by myself for me time.  I can't imagine it.  He micromanages my whereabouts in the house.  He pressures me.  He won't sleep in his room.  He will fall asleep in the living room on the couch, but I have to stay out with him until he does, and if he wakes up and I'm not there, he comes to my room to get me.  This can happen several times a night.  It feel like I have a toddler forever.  He has always been this way, but it seems to have exacerbated since my husband and I are going through a divorce.  He also has developed a terrible fea of bugs.  My husband and I still live under the same roof, due to economic conditions.  But, my husband does have a girlfriend, which I only found out about 8 months ago.  But, before I found out, he had been dragging my, than 10 year old, along with him to see her.  He'd take him to the community poot to meet her, her house, and for walks at a local lake.  My son told me his dad would tell him "Don't tell your Mom".
I don't know if this is what has made his behavior more prevelant though.  He has basically has had the problem since, it seems, birth.  But now, his fears, being alone and bugs, has gotten worse.  And, I'm the one who has to deal with it.  I don't know what to do to help him.  But, I need to be able to get help before the divorce is final and I'm back to work fulltime.   Please help.  Thanks.  Any suggestions would be well appreciated.
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