Sent from your computer or sent with your email address as the sender? There is a big difference and the later is usually what happens. If they were sent from your account they would be in your sent folder.

It is still a good idea to change your email password ASAP and notify your contacts that this is happening. One way to let people know that emails with your address are from you is to establish a signature for your emails. Spammers rarely go to that trouble.

https://support.mozilla.org/en-US/kb/signatures

Thank you. Yes, they are not being sent from my computer, just with my email address as the sender. I will change my password now. Do you think that will fix it? I do use a signature file, but the fake emails do not have the signature attached.

You cannot stop it. They have your address and are sending from someplace else. They are not using your account. They will get bored with you and move on to the next victim soon.

Just inform your contacts that real messages from you will have the signature and not to open any links in the fake ones.

Be protective of your personal info. Do not always provide the info just because they ask. Just like lots of sales counters ask for you phone numbers at time of sale. Tell them to take a hike. They do not need your number to take your money. Email addresses are the same. You would not believe the number of people that post their addresses here on this open forum and ask why someone has scammed their address. Sorry it happened to you but it either has happened or will happen to everyone sometime.