I’ve been bed bound for 6 years, will exercising give me a heart attack if I have a family history of heart problems?

I (36F) have been more or less bed bound because of depression for the past 6 years. And I really mean that. I barely walk around the house. My blood work is good (I’m on Atorvastatin for cholesterol but it’s a low dose). I’m a healthy weight. I eat regularly and not a lot. But I feel like my muscles have completely atrophied. And the one I worry the most about is my heart. My dad died of a heart attack at 67, and my mom had an aortic aneurism which resulted in having to have her aorta replaced twice (once at 46 and again at 56), and was just diagnosed with Afib at 70. I just walked (went from slow to a faster pace but not running) on a walking pad for about 15 minutes and my bpm went up to 137 bpm, and I felt woozy. Am I at risk for a heart attack going from being stagnant for so long to moving?