No no no no no.
You have to leave - I am so sorry but you HAVE to leave.
You're 23, with your whole life ahead of you.
You have all the time in the world to find someone who won't lie to you and use violence and suicide threats to shut you up and maintain your facade of a relationship.
This isn't going to get resolved. Firstly, he is bisexual, so no , you are never going to be 'enough' for him. That's not your fault, any heterosexual relationship he has will present him with the same problem. (However, I'm not surprised your self-esteem is rock bottom when he spends all his time lying to you about his cheating).
Secondly, he's a cheat, and this is FAR more important than the bisexuality. He lies and lies and lies, and he cheats. He's even lied to you about past girlfriends, so it's not even as if this is all about his confusion over who he wants to be with - man or woman. He just Is A Cheat.
If you stay with him, this won't change. He might decide he's happy being in a heterosexual relationship and stay with you, but he'll probably still lie and cheat and be on hookup sites, because he thinks this is ok. If he didn't think it was ok, he wouldn't do it. Bisexual doesn't mean constant lies and hookup sites. Being a cheat is the cause of that.
Also, he clearly has strong feelings for men. There's every chance he will eventually decide that he wants to be in a homosexual relationship, or have a male as his primary partner. Do you want to risk that? Do you really want to be ten years down the line, with two kids, when he announces that he can no longer live a lie and he's gay, and bye bye?
Finally - the thing that stands out most of all from this is quite simple. He's just not a very nice man. He's a liar (did Imention that already?) He won't talk about things which are important in your relationship. He uses threats (suicide) to get his own way. Your self esteem is rock bottom. It's not a nice relationship. You are young. Let me tell you now that your 40-year old self will be screaming at you NOT to let this jerk be the father of your children or your life partner.
You 'love' him, but this is a shit relationship and he certainly does not value or cherish you. Please, move on!!