i cant really tell the canopy from that behind ... i almost wonder if its historically been topped ... the depth of the pic is just confusing ... the broken branch looks like wind damage.. or mechanical [big truck tear?] ... its not a rot issue ... as noted.. the ants are the best sign that something else is going on ... either they were farming aphids ... or the tree is rotting on the inside ... they are advantageous... not causal .... listen .... all trees are disposable .... its brand new to you ... if it continues to displease you ... after next year... just get rid of it ... dont go all tree hugger.. on a tree that pisses you off... be done with it but i wouldnt go making decisions on your 2 months with it ... its fall... [coincidental to you thinking its been going downhill a month ago].....probably been a long tough year weather wise ... for many of us .. etc ... if you come back.. always try to tell us.. where you are ... sometimes it matters... ken ps: that is not a big branch .. lol ....

It's not just whether a given tree can "recover" from such poor pruning, it's what the long-term ramifications will be; All those stubs left all over the place will indeed likely have previously dormant buds "released" by the removal of the buds at the ends of the branches-the parts that are now gone. So far so good-the plant will appear to fill back out with live foliage. But the tree can't compartmentalize when branches are lopped off willy-nilly as seen here and consequently, there will very likely be a pocket of decay at the ends-or what are now the ends-of each branch so severely truncated. Even this might not matter so much if this is a species that matures at a low height, etc. It will be full of funky things but nobody will ever know that except for the OP and us readers, lol. But if this were a tall-growing species, having all that decay left up in the crown quickly becomes hazardous. Around here, the prime example of what I'm talking about are large, old silver maples, growing under wires, where the powerline clearance contractor has used less than stellar technique, leaving stubs behind. In each and every such case, regrowth of new sprouts has been explosive, but way back where the random cut was made, there is a well-defined pocket of decay, which can now travel down through the branch and even get into the main trunk. None of that might matter here if the OP keeps this tree small somehow. But that by no means should be used as an argument that this pruning was acceptable.

I would just remove the suckers from the bottom. Technically CMs are shrubs, so the mulch shouldn't cause too many problems. You could run a lawnmower over the mulch, and remove the adventitous roots, but this will likely create more suckers, making it more maintenance. See the link below for proper pruning. ==>>>http://thedailysouth.southernliving.com/2009/02/24/what-concerns-p/

when i see those vertical lines of whatever.. along the edge of the trunk ... id bet my shiny penny .. that the wound will open up to that extent ... in the next year or two ... just under the bark.. is the cambium layer .... the vascular system of the tree ... water up.. food down to be stored in the roots ... the cambium is lost in that entire wound .... so its going to have a hard time keeping the top alive ... and probably has for the last few years.. hence your noted limb loss ... if you are going to plant something ... better get it done soon ... or wait until fall planting time .. im not quite sure of timing for your area ... never plant in the heat of summer ... but if you find a tree you like.. if the timing is wrong.. you can 'hold it over' until the next proper planting time ... ken https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub