Rejection of Rescue Novel

I just received a rejection of my Rescue Novel from Boroughs Publishing Group.  They promised a reply in sixteen weeks.  When they went beyond that goal for a reply I emailed them reminding them of how long it had been since my submission.  A few or more days later they sent me the rejection email.  I have finally come to realize that, especially at my age, the only route to go for a novel submission is not to go to a publisher but do it the self-publishing route via KDP.  I did a lot of research on this novel and also got two beta readers to go over the novel.  I incorporated their suggestions into the final version of the novel.  Their suggestions were very good so the novel is now well polished.
I plan to self-publish via KDP hopefully after the first of the year assuming my health is better.  I will employ a cover artist, probably the same one who did my last novel, and when the formatting is complete I will take out an expensive ad in my RWR magazine, probably a full page ad.  Depending on the results of that this may be my swan song for writing other than the Mary Magdalene story I am presently working on.  The RWR magazine is Romance Writers Report a publication of RWA, Romance Writers of America which will reach over 10,000 readers, authors, editors and agents.