I have an ethernet cable however every time I share my internet I lose it.

Fact of the matter in trying this; appears to be an issue, along this line:

WARNING:

"..If your internet connection and your local network use the same port (Ethernet,

for example), investigate possible side effects before you turn on internet sharing.

In some cases, sharing your internet connection, disrupts the network..

..If you use a cable modem, for example, you might unintentionally affect the network

settings of other ISP customers, and your ISP might terminate your service..."

~ above cited in reference article by ku4hx.

PS:

• Connect your Mac to the Internet using Ethernet

Set Ethernet hardware options if your network requires it and your network service

supports it. See Change advanced hardware options or Use Gigabit Ethernet.

Does "people just say" mean this? Share the internet connection on Mac with other network users - Apple Support

If not, you need to follow Apple's guidance on sharing and retry.

I should think that there’s probably an easier way than using your Mac as an awkward Wi-Fi router, or as an award IP router, but some details of your network configuration would be helpful in determining the best path to achieve that. Most ISP connections include a Wi-Fi router, too.

What does this network look like? What are the boxes and cables and related connections from your ISP to this Mac?

Your image indicates you are trying to share a WiFi connection when you state you have an Ethernet connection to the Internet. Follow the instructions at the link provided by ku4hx.