Abortion Scheduled - still not sure

(Sorry for the length.). My abortion is scheduled for Wednesday morning & I'm really conflicted about what to do. Please no hating. I made a mistake. I am married, but my husband has chosen to live away from me. I haven't seen him this year & only for 4 days last year. He maybe responds to my messages once or twice a week & often, it's to ask me to send him money. I am 36 & no children yet. I have always wanted to have children, but we are never together enough & I'm aware that my window to have children is getting shorter. I should also mention I lost my job in January & have been unable to get a job since. My employer tricked me into signing paperwork that waived my right to unemployment benefits, so I am truly broke with no help from anyone. I cashed in more than half of my 401k just to cover rent through the end of July in hopes I will have a job by then. 
Well, I ended up sleeping with a friend who is also married & has children. I am now pregnant by my friend. I don't want to mess up his life with his family. 
So, if I keep this child, I know for a fact my husband will divorce me &, since the father has his own family & I can't mess that up for him, I would be raising this child alone & with little (currently no) income. I don't know if that would be fair to the child. And, even though I have a lot of love to give, they will always wonder & think about why their dad isn't in their life. 
So, after talking with the father, I scheduled an abortion. While I don't judge others, I honestly never thought I could have one myself. Knowing that it already has a heartbeat... It just breaks something inside of me to think that I will be stopping a beating heart with my actions. I'm not sure I can live with myself afterwards. 
I just don't know what to do. My mind says abortion, but idk. It's scary that I don't feel firm with my decision & I only have 1 more day to really make a choice. 
I should also mention that have have been diagnosed with depression & anxiety, but stopped taking my medication in January when I lost my job & could not afford the medication anymore. I'm afraid whichever decision I make, I will regret it & that will really set me back in regards to my mental health. 
BTW, I tried calling the BackLine support group 3x today for some advise, but got an answering machine every time. :(
I should also note that I know in my heart that I could not carry a child for 9 months & then place it for adoption. That is not an option for me. 
Please no judgement, but I would really appreciate any advise you can give.