Wiring combo outlet & switch but box w/ 3 wires

Since you broke the tab, you have (electrically) two separate devices, so you will need one extra wire instead of two. But no big deal.

You will need one extra piece of black wire and one extra piece of white wire, and two wire nuts to replace the existing wire nuts.

Screw colors are based on the picture & instructions from the linked switch. Others may vary somewhat.

• Existing black switch hot wire (the one that is combined with two others) goes to black screw on switch (top right if switch on top)
• New black wire connected to the other three black wires in a wire nut and to the black screw on receptacle (lower right)
• Existing black switched hot wire (the one that is by itself) goes to brass screw on switch (top left)
• New white wire connected to all the other white wires in a wire nut and to the silver screw on receptacle (lower left)

One of the 3 black wires is hot. Your switch side could go in the way it was to the new switch. Connect the silver screw to the white wires (for the outlet side) a pig tail works best here. What you have to figure out is the hot wire, not hard. You know the black you hooked up to the outlet is not the hot . So you have 2 other choices once you have the correct hot on the outlet run that to the hot side of the switch and the other 2 wires depend, 1 is the light, and you know it goes on the other side of the switch. The last of the 3 blacks may be another receptacle if so put it on the hot side. If it is a second light put it on the black switched side. In this case if you keep blacks separate from white you can mix and match until you get them correct. If you also want this receptacle switched feed the switched contact over to the black of the receptacle and you are done. Make all changes with the breaker off for safety and let us know you got it.

The most likely wiring combination for that switch/receptacle would be ; the black wires with the wire nut would be hot to the switch and receptacle, the single black wire would go to the light as the switch leg and the whites would be the neutral for the receptacle. Use a voltage meter and check it out.

Voltage from the blacks and white with the wire nuts should be 120V, and powering the single black wire should light the light. Hope this helps.