Suffering 5 year relationship at a head, strange 2 year friendship being tested.

Ok so let’s bring this back 5 years ago to when I first was dating my boyfriend. Things were great but we began having difficulties after a long while of being together. I began feeling very neglected mentally and was crying out for help on deaf ears. This resulted in a breakup. Now here is where I’m just as guilty. During this break up I had an unhealthy habit of seeking “love” from people who did not care about me. Months later my boyfriend and I end up back together. Only for the same cycle to happen. This time I began getting very close to his friend/roommate who did not make his intentions clear, this resulted in a very strange and confusing ordeal of emotions for myself and others involved. Fast forward more time, I this time apologizing profusely and just feeling like the scum of the earth. That was over 3 years ago. Things we very good again for a long time until we both left our jobs (we worked at the same place and left for the same reason poor management) then things turned again. I bounced back quickly and got a job which I still hold to this day, he did not. He sunk into a deep depression and it took him a very long time to get work. When he finally did he quit after about 4-6 months for various reason. Since then he’s had no work and has been spiraling into a rut. All the while this is happening both of our immediate family members (my mom and his grandpa) become very ill and begin a fast decline in health. This took an even bigger toll on both of us. During his whole spiral of depression I have noticed a major change. The sincerity of his gifts is gone, his attentiveness began to dwindle among many other things. All the while I pushed these feelings aside as I felt I would be out of line to say anything. He’s in just a dark place mentally as I am. Who am I to judge? Over the oast two years I began working with my best friend who now has crossed a strange line. After he moved on to another job and left his very volatile relationship of many years we began hanging out much more. During this time I’ve felt things were going in this path but once again I ignored it until to let to a kiss one night. A kiss I then continued. And did again multiple times later. Truly I’m disgusted with myself as this is so far from my own morals and I’m shocked at myself. I then found myself thinking maybe it could be him? But looking at how he has treated others and the strange relationship between his daughter his something that’s scares me. Sure he’s grown but how much? After feeling so much gulit I finally separated myself from my friend to think and tried to talk to my boyfriend about everything but my friend. It’s not going well. I don’t know what to do…