As a mule momma myself, I say go for it! I have had three mules, and still have the one I raised from a colt (I raised two from babies). They're great! I can totally understand wanting to have a baby mule from your horse. Just make sure you don't run into conformational or medical issues with your mare + the jack. And make sure the jack will breed a mare. Some will breed only jennets.
Also, please bear in mind a mule is DIFFERENT from a horse! It is not a long-eared horse. A lot of the differences are beneficial, like a mule is an easier keeper (can live on worse food and less water), is usually stronger and more resistant to issues (why New Orleans banned horses to pull their carriages and only allow mules), usually tries to figure things out instead of bolting, won't eat itself to death, usually has tougher feet, etc. But a mule thinks differently from a horse--it has a very strong self-preservation drive, so you have to partner with it and convince it you want it to do something instead of just telling it, like a horse. The main thing to keep in mind with a mule is that it is always saying, "What's in this for me?" Mules also take longer to mature/develop than horses, and breaking and riding need to wait until about four years old (they fully mature around five or six). There's also the need for different tack, as mules are usually shaped differently from horses--often narrower, with low or no withers. You will probably need a saddle with mule bars and you will need a crupper. That said, my first mule was built just like a quarter horse and took a regular quarter-bars saddle. But she needed a crupper if we were trail riding anything other than flat land!
The other thing is making sure the folks around you know how and are prepared to deal with mules (trainers, vets, farriers, etc.). NEVER send your mule to a trainer who says, "Oh yeah, I broke me a couple mules before. They're just like horses." Mules have long memories and don't forget bad experiences.
If you understand these things and do your research, mules can be VERY rewarding.
My first mule, Miz Blue. She loved trail riding! I rode her in the grand entry to the rodeo once, and everyone thought she was a horse until I got close to them. The double-takes were great! 1st day on property! W dogs.jpg
Here's my current mule, Blackjack, when he was little: new colt 027.jpg
And here we are now: Walking toward camera.jpg
And here's my pony mule baby Sassafras (Sassy) at one day old: Baby mule looks 5-18-05.jpg
And later, when she was about two. She LOVED to be with people. She always had her head under my arm when I was cleaning the water tank or doing something around the property. I traded her and Blue for training for Blackjack from a top mule trainer. I miss the little sweetie! Sassy stands tied 10-29-05.jpg