I want to be a Dom but I'm having some trouble

I really want to be the dominant one more often in the relationship, my partner wants me to as well, but I have a hard time struggling with it. I feel conflicted, a part of me wants to let this side of myself come out and another part of me judges me for it. I'm one of those types of people that manages to stay calm when everyone else is angry, so showing this really deep part of myself when I've never shown it before is a big struggle. There's a part of me that feels like if I act Dominant then I'm being "too selfish", even if I know my partner has expressed she wants me to. Leading up to it, I'll feel like "Yeah! I'm going to do it this time!" but I'll freeze and back pedal or just suddenly feel unsure of what I should even do.
Even worse still, I know I'm a sadist, I just haven't fully tried anything yet to know how much of a sadist I am, and I go back and forth between feeling proud or ashamed of it.
Obviously I have my own insecurities to get over, but I haven't met other Doms at all really, I mostly bump into masochists, so I'm trying to see if someone would share a similar story with me or give me some advice on how to slowly ease into a Dom position so that I and my partner feel comfortable.
The last thing I want is to throw caution to the wind and blindly rush in.

You don't say how you both envisage the Dom/sub split manifesting itself; sexually or in a daily life manner? Or perhaps a little of both? I'll assume sexual.

You connected anger and Dominance: I suspect that was probably more a confusion of words but I certainly do not think they fit together. A Dominant will usually be assertive but we should carefully examine any anger we may feel towards our submissive to understand:
1) why we are feeling angry with her and
2) to ensure anger does not corrupt the power we hold and use.

How to be a Dominant?

My automatic response to that question is to ask back, "Is it within you to be one?". I knew from before puberty that I was a dominant male and that trait gradually developed as I grew older not only within my sex life but also in the way I interacted with others in daily life. If, in your heart, you know that Dominant "need" is there then pursue it but if you don't feel it then don't waste you life chasing dreams.

>showing this really deep part of myself when
>I've never shown it before is a big struggle

It is, isn't it.

Coming to terms with a part of myself which wants to control, dominate and use another for my own ends and pleasures has been difficult for me and I still (after 40+ years of such activity) am not able to unfeelingly "use" a submissive and I'm very glad about that. I like that I still feel a touch of guilt, I like that I still worry about her pleasure and her welfare and even on those occasions when I do "use" her because I know it's what she wants too I like that the caring side of me is constantly checking and monitoring her to ensure she is OK. It is that guilt and concern which tell me that although I am a sexual deviant I am not a sociopath.

How to be a practicing Dominant?

Like most things... start small and work up.

One evening take her out to dinner but instruct her not to wear any knickers. And in the restaurant, when appropriate, discretely slide your hand up to her pussy. I can virtually guarantee it'll be very wet

After the children are in bed instruct her to go topless and put some handcuffs on her for the evening, it's enjoyable watching a submissive in handcuffs pour a glass of wine

For a more intense BDSM session (again, go slowly) ideally tie her, with her hands overhead, to an overhead (ceiling) point, if that's not possible then spread-eagled on the bed. At this stage I suggest you, securely, blindfold her but *do not* gag her. I suggest the blindfold to provide a degree of anonymity (no eye contact) but no gag because you are learning one-another and need clear and open communications.

Slowly, gently and carefully are the watchwords now that you have your beautiful naked lady tied and at your mercy.

Sensation play: an ice cube passed across her nipples, a stiff hairbrush down her back, a silk scarf across her breasts....

Impact play: make or buy some light floggers and paddles, perhaps a cane, use these (gently) over her body.

Whisper in her ear that "You are mine", "Totally at my mercy", "Mine to do as I wish with" and similar.

Observe her reactions to each of your actions, she won't say much, if anything, and you should not ask "How was that?". Learn to read her, what she likes what she doesn't. After your session is over a debrief is good. It takes time to get to know one another BDSM wise and only once you have achieved a connection will you be able to determine how far you both want to go down the road of power exchange.

I've waffled long enough - good luck and much joy to you both.

James