I have many health issues; should I be seeing a cardiologist as well?

Am 77, a widow, CHF due to chemo after mastectomy in Feb 2002, triple bypass Sep 2002, but never had a heart attack. Have Diabetes, on 2000 mg Metformin twice daily as well as 40 units insulin (Novolin 70/30) twice daily. Am about 60# overweight. Recently learned I have pulmonary hypertension. Have sleep apnea, use C-Pap machine at night. Pulmonary specialist plans to put me on daytime oxygen. Should I also be seein my cardiologist? What is my prognosis for the future?