Hi VJ, I totally understand your thoughts on this. My D was 18 when her dad and I separated. After dating on and off for about 3 yrs, I met someone and we are now living together. Neither of us have kids at home. Your kids are at an age when "it's all about them." However, in a couple of years they may feel differently about your BF. My D was "relieved" when I found someone because, until then, she felt like she was all I had. She worried about me constantly and now she feels less pressure to "be there for me." Your kids need to understand (and eventually they will) that you can't put your life on hold indefinitely to cater to their needs. They will grow up, move out and have their own lives.
I didn't read all of your post on the neediness of your BF, but, it may be that he just wonders where he stands in relationship to your kids, job, etc. This is normal and it's something that we all need to know.
As for being scared, looking for excuses, etc., this is also normal after what we've been through.