Should I quit the company I founded?

I will try to make this short. About nine months ago my ex boss offered to invest in a company for me. Our relationship even when it was not romantic was deeply emotional. I care a lot about him as a friend. I started a Digital agency and worked on the branding aspect of it. We build a few in-house tools, built our marketing, worked on market research and due to my budget I could not hire a seasoned sales person. I had a great team and brand but no money coming thru the door.

He did not want to sign anything at that time so we didn't have a contract in place and every other day he would tell me to shut it down. We were into month four since researching point and he wanted to replace me as CEO. Now I found some people and introduced him to them and all they were after was the funding. He gave them the same agreement as me and made him CEO. Now even when I still have a job, I feel unmotivated and angry as I feel that I was not given a fair shot. I put my heart and soul into this, but the investor doesn't believe in me. I learned my lesson as friendships and business do not mix but I feel used. I honestly feel like all of my ideas are being taken away and after all the hard work they just replaced with whom they feel has a better look for a CEO position.

Should I stick it out as I am still vested for 4 years to get 15% of what I created or should I take my losses and leave. I am a nervous wreck, emotional and just plain unhappy. Need to add that I am a single mother as well. This is a great concept and we have a group of very creative people on board that were there prior to the take over, but my spirit is broken.

Thanks in advance for any advice.

Only you can answer this question. But the fact that you are saying you are "a nervous wreck, emotional, and just plain unhappy" is a big red flag. It's always a bad plan to stay at a job (startup or not) that doesn't make you happy.

It's hard to leave a company you founded. I had to because we ran out of money not because I was forced out.

As @rbwhitaker said, the decision is up to you.

The only guidance I will give you is life is really too short to be unhappy. Money cannot replace the utter joy of life. You need to find what gives you joy and do that.

I went through something similar a couple years ago. I spent two years trying to accomplish the impossible. The company rode its way to an IPO on my back. As soon as the money came in, they set me up to fail and used the excuse to demote me. Soon thereafter they found a way to lay me off. To top it off, a year later they ended up doing the exact same thing to my replacement.

I am telling you this because your boss sounds a lot like my ex-boss:

1. He refused to put anything in writing.
2. He threw me under a bus once he no longer needed me.
3. He manipulated me the entire time, making me believe he really cared.

If you're unhappy, four years is a very long time to wait. More importantly, it is highly unlikely that you're going to see any of that money. If they want to get rid of you they can and will find a way.

There's an easy way to prove my point: Go to your boss today and ask him to put the agreement in writing. I'm willing to bet he won't do it. My ex-boss said he would, yet week after week would go by and he wouldn't actually do it. A few months later he showed me the door. One way or another you'll get your answer. Give it a try.

If its your company and you put hard work into it I would battle it,
get a lawyer get the most $ you can out of it, then bail the ship and focus on something new

As @rbwhitaker said, the choice is up to you ... but as someone who has been through this before (like @Gili), I would lean towards quitting. In the end, you're happiness is going to be more important than money. If you are good (as it sounds like you are), you'll make your money elsewhere. I've started to believe strongly that when "one door closes, another opens". Good luck in your decision, it's not easy :(