Not inviting ex-coworkers. I feel bad...

We have a max capacity of 140, but can accommodate 150 in our venue. We will be inviting 147 (in hopes some will decline), of mostly all family. I have about 10 ex-coworkers (including s/o's), who I want to invite because I worked with the for 9 years, but can't. They all think they're invited, and they would be, if we had a bigger venue and could afford the extra $90 per person. How do I tell them there's just no room for them? We already had to cut back on some family members because of the lack of room. I don't want to move to a bigger venue, because it keeps costs down and it's the location and view we want. I just feel so bad...