How do I keep from crying at work?

Okay, so I'm 49, single, and my kids have all moved away. I've finally reached the stage where my periods are irregular, I'm exhausted, and if I don't have anything pressing, I'm sleeping. I'm not cranky or moody, just internally sad, mostly because I'm lonely. I work in a male-dominated field. Most of my coworkers are great young men in their 30s. Besides the job, we have nothing in common. They all get together outside of work and play ball, drink, etc., and when they come in, they're all so friendly and get along so well. They have their inside jokes, and it's a great culture—for them. I never let on that I'm disappointed that I'm not included. My colleagues are great to work with. They are all smart and hardworking and never slack on the job. They are also never disrespectful to me in any way. They are great guys, and we all work well together. On top of that, I don't expect them to include me in activities outside of work; frankly, they have nothing to do with me. It's not their fault or responsibility to manage my emotional state. So I never let on that I feel left out. I know I am just lonely. I had eight children, and now we all live in different places; I don't get to see them often. I don't live in my hometown and had a bad breakup a couple of years ago, so I don't have any close friends. Recently, I was assigned to work with a team member I rarely work with. In casual conversation, he asked about my family, and I felt myself choke up. I had to excuse myself, playing it off like I needed to go to the bathroom.

I know my hormones are a mess, and I don't want anyone at work to think I am an emotional wreck.

How do I deal with this?